Competence is a necessary condition before a physician can accept a patient's treatment consent or refusal. Competence confers decision-making authority on those who are competent, while disenfranchising those who are not (Beauchamp). A determination of patient competence promotes respect for self-determination as well as patient participation in healthcare and other decision making. In most nonemergency situations, those who are legally competent may consent to or refuse healthcare. A patient maintained for years on outpatient hemodialysis, for example, may be allowed to terminate hemodialysis, resulting in death, if the patient decides that he or she can no longer tolerate the stress of the procedure (Neu and Kjellstrand). And based upon religious reasons, a Jehovah's Witness may even refuse a blood transfusion that would otherwise save his or her life. In contrast, the consent or refusal of those who are legally incompetent or clinically incapacitated need not be respected. A psychotic woman who refuses to have a cardiac pacemaker inserted because she believes that others could then monitor and control her activities would not be permitted to refuse this lifesustaining surgical procedure. Competence is usually not a relevant issue in healthcare emergencies, when treatment delay would be substantially harmful to the patient.
Competence and autonomy are often conflated, although their meanings are quite distinguishable (Beauchamp). Competence allows a person to exercise his or her autonomy. One must be autonomous to be competent, yet competent persons may act nonautonomously when, for example, compelled to do so by another person. Further, an autonomous person may act incompetently (e.g., a professional negligent at work).
This entry considers some of the issues in defining, determining, and assessing competence, as well as some of the applications of competence to the field of mental healthcare.
Generically, "competence" means simply the ability to perform a particular task (Beauchamp), although it has often been used loosely in several senses. In healthcare contexts, competence is the capacity to make autonomous healthcare decisions (Morreim). In most accounts of competence, competence is specific to the task or issue, since a person may be able to perform one task but not another. Few people are globally competent or incompetent. Since one's abilities change over time, in either direction, competence is also specific to time. Abilities may also be a function of the conditions or the situation in which they are tested or the person who tests them.
Competencies, of course, relate to all areas of function (Grisso). While competence to consent to healthcare or research is of primary concern in the present context, issues are often raised about a person's ability to work, manage personal finances, make a contract, write a will, live independently, drive a car, marry and divorce, parent a child, or testify in court. In legal contexts, competence questions arise in civil actions as well as in criminal litigation (competence to stand trial, commit a crime, enter a plea, or be sentenced) (Bonnie). Legal competencies implicate past decision making (e.g., competence to write a will), present decision making (e.g., competence to stand trial), or future decision making (e.g., competence to manage one's financial affairs).
A person's competence may be questioned in more than one area. In the case of a mother with cancer and a psychotic depressive disorder who is separated from her husband, for example, questions may arise about her capacity to parent her children, manage her finances, and consent to medical or psychiatric care. If she were employed, questions may arise about her ability to function at work if she failed to meet deadlines or otherwise fulfill her job duties due to a medical or psychiatric disorder. Her or her husband's attorney may question her ability to consult with her attorney and participate in the divorce litigation.
This contextualized, decision-specific notion of competence may be contrasted with a more generalized conception that reflects the general legal and moral autonomy enjoyed by most adults in contemporary Western cultures (Wear). Many more adults are considered competent under the general conception than the task-specific one; therefore, establishing that a person is incompetent is more difficult under the former than the latter.
"Incompetence" has come to mean the loss in court of a person's legal right to function in some particular area. Such a narrow legal definition of competence or incompetence contrasts with the more common clinical use of incompetence according to which a person has a legal right to function but is unable to do so. Clinical and legal competence may not correspond. An elderly, demented person, for example, may have the legal right to drive a car or make his or her own healthcare decisions but may no longer be substantially able to do so. Similarly, an adolescent may not be legally competent to consent to healthcare but may be clinically or functionally able to do so.
The increasingly prevalent view is that individuals have various specific abilities or capacities as well as incapacities, each along a continuum. A person is considered incapacitated when the person is no longer able to perform that specific function and incompetent when a court has so ruled. Legally, there is a presumption of competence, which may be overcome when the court is presented with adequate evidence of incapacitation. In the clinical literature, however, competence refers either to an individual's capacities (a descriptive definition) or to whether that individual's particular capacities are sufficient to render legal decisionmaking authority to him or her (a threshold definition).
Finally, although competence usually refers to a person's abilities, it may also refer to his or her actions or behavior (Beauchamp). For example, a person of general competence may autonomously choose to act incompetently in a given situation (e.g., intentionally fail an examination).
Because functional or decision-making capacities occur on a continuum and because a person's capacities can be expected to fluctuate over time, in most cases a clinician need not be resigned to accept a patient as permanently incapacitated. The clinician frequently has opportunities to enhance the person's functional or decision-making capacity. Hearing aids, eyeglasses, psychotropic medication, counseling and psychotherapy, and specific behavioral training in the area of incapacity are examples of remedial efforts that can be made to improve a person's capacity. When such efforts fail, disposition of those who are incapacitated is a complex matter and varies with the context in question. In a case where life-saving treatment may be needed, the clinician may have to obtain an adjudication of legal incompetence in order to treat an incompetent refusing patient.
Although competence is a necessary precondition to respecting patient choice, incompetence is not a sufficient condition to overriding it, contrary to much clinical and lay understanding. The clinician may wish to, and often should, respect a person's preferences even if the person is legally incompetent or functionally incapacitated. The clinician may ask a young boy with which parent he prefers to live following his parents' divorce; the clinician probably will ask an elderly, demented woman whom she prefers to manage her estate should the appointment of a legal guardian be authorized.
Before intervening over the person's objection, the clinician needs to specifically assess the risks, benefits, and alternatives; this includes an evaluation of the potential harms of a proposed intervention to the person. Overriding treatment refusals, whether by a healthcare professional, family member, or court, ethically and legally requires evidence that (1) such treatment would benefit the patient (the "best interests" test); (2) such treatment would have been the decision of the patient had he or she been able to make the decision (the "substituted judgment" test); or (3) the patient had provided some previous direction or instruction about the treatment in question ("expressed interest" test). The test of substitute decision making varies with the decision, the decision maker, and the legal jurisdiction. Use of the substituted-judgment or the expressed interest test, in contrast to the best-interests test, better respects the person's autonomy and self-determination.
There is no international clinical, legal, philosophical, or ethical consensus about competence criteria or standards, and many are in use. In other words, there is no agreement about the threshold of decision-making or functional capacity necessary to consider a person legally or morally competent. In a given case, there may be wide consensus among clinicians, legal professionals, and ethicists that a particular person is, or is not, competent in some respect; however, disagreement is likely in many cases. In part, this derives from the fact that competence determinations are not essentially factual, objective, or empirical matters but rather are value-laden judgments about the relative importance of autonomy and beneficence to the person, as assessed by the clinician or others. Competence is typically inferred from the person's behavior and thinking rather than observed directly, and evaluators may differ in their judgment of the person's competence. Such differences about the person's competence occur in part due to evaluators' varying perceptions of the person's values or of the person's rationality. Under the most common view, competence is not a fixed property of an individual applicable to all decisions and all potential risks; rather, competence is a context-dependent, decision-specific, interpersonal process (Buchanan and Brock; Drane).
Criteria for competence involve whether the person can make a choice, communicate that choice, understand relevant information about the choice and its alternatives, and rationally manipulate information about the choice and its alternatives (Appelbaum and Grisso). The person must be able to apply the relevant information about a prospective decision to his or her own case rather than in the abstract or as applied to someone else.
The influential U.S. President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research adopted a standard of capacity that requires (1) possession of a set of values and goals; (2) the ability to communicate and to understand information; and(3) the ability to reason and to deliberate about one's choices(U.S. President's Commission). This standard emphasizes the process of reasoning or decision making rather than the particular outcome of the decision. A competence standard that focuses upon the outcome of the decision can be faulted for granting greater priority to the values of the person assessing the patient's competence than to the values of the patient.
A similar definition of competence is offered by the Canadian province of Ontario: "Mentally competent means having the ability to understand the subject-matter in respect of which consent is requested and able to appreciate the consequences of giving or withholding consent" (Ontario Ministry of Health). This "appreciation" component, however, involves emotional rather than strictly cognitive considerations, and broadens the competence standard.
As noted by the U.S. President's Commission, assessment of the individual's current and previous personal values is an essential component of evaluating competence. Obtaining a values history for the individual provides critical information about the person's past major life decisions relevant to the present decision making. Judgments about a person's competence must be individualized according to his or her attitudes and values history rather than reflect only the person's knowledge, skills, and cognitive capacities.
It is unrealistic to expect that competence criteria are, or will remain, fixed over time. Competence criteria are likely to evolve as society seeks to resolve the conflict between the competing principles of respect for autonomy and concern for the person's well-being.
SLIDING SCALE OF COMPETENCE CRITERIA. The predominant approach to selecting competence criteria, at least with regard to competence to consent to healthcare, depends on the actual decision at issue. In this scheme, named the "sliding scale, " the criteria for competence vary with the particular decision and its risks and benefits. As the risks of the proposed healthcare increase or as the benefits to the proposed healthcare decrease, more capacity is required for the patient to be considered competent to consent to the healthcare (Drane; Roth et al.). For example, it is less difficult to decide to consent to a course of conventional antibiotic medication for a urinary tract infection than a course of experimental chemotherapy for stomach cancer, and less capacity should be required to do so. Likewise, more capacity is required for the patient to be considered competent to refuse healthcare when its risks decrease or its benefits increase.
Although the sliding-scale approach to competence criteria is commonly used in healthcare decision making, some problems accompany its use. Given the strong bias of healthcare professionals—and society—in favor of treatment, one concern is that professionals will manipulate or selectively use those competence criteria that result in labeling competent someone who consents to healthcare, while labeling incompetent someone who refuses care. Another concern of the variable standard approach is that, counterintuitively, a patient could be considered competent to consent to a particular intervention but incompetent to refuse that same intervention (Buchanan and Brock). This may occur because refusing healthcare is more complicated than consenting to it, but here too a protreatment bias is evident.
Clinicians frequently make informal judgments about a patient's competence in their daily work; but some cases, such as treatment refusals or consents by questionably competent patients, necessitate formal, detailed assessments. Competence assessments should focus on the specific area of function in question. Assessments of global or general competence are unlikely to adequately respond to the presenting question. Among the procedural considerations in conducting competence assessments, the time and place of examination and the need for reexamination are especially important (Weiner and Wettstein). These assessments sometimes use written structured or formal assessment inventories of functioning, observational functional assessments(e.g., observing a patient grocery shopping and preparing a meal), psychological testing, or formal psychiatric interviews. History taking and collateral reports from third-party informants such as family, friends, and other healthcare personnel can be valuable additions to individual contact with the person being assessed. The examiner pays particular attention to eliciting information about the patient's decisionmaking history and the values he or she has placed on personal autonomy, healthcare, disability, and death. Consultations with colleagues or second opinions may also be helpful to the examiner in difficult cases. In general medical hospitals, competence assessments are conducted initially by nonpsychiatric physicians; if necessary, psychiatric consultants are called to assist in the evaluation.
Competence assessments raise many problematic clinical issues including denial of illness; subtle forms of incapacity; impact of elevated or depressed mood on decisionmaking capacity; fluctuating mental status (due to intermittent treatment compliance, the natural course of the disorder, or side effects of treatment); treatment refusals based on religious reasons; lack of information about the patient, including personal values and goals or history of treatment refusals; lack of formal staff training to do competence assessments; and disagreements among staff about the appropriate competence criteria or threshold. Typically, competence is not challenged, investigated, or formally assessed in clinical practice until a patient refuses treatment or is noncompliant with it.
Competence and Mental Healthcare
The presence of a mental disorder does not automatically negate the presumption of a person's competence. Although some severely mental ill persons are indeed incapacitated in many areas of their functioning, most mentally ill persons have only some discrete areas of decision-making incapacity, often confined to episodes of their illness. A paranoid delusional patient who denies that he is mentally ill, for example, may be unable to rationally decide whether or not to consent to antipsychotic medication while he is mentally ill but may have adequate decision-making ability to consent to treatment for diabetes and heart disease. In such a case, the content of the patient's paranoid delusions would be irrelevant to the patient's diabetes and heart disease, and the patient would not deny the fact of his medical illnesses. A patient in a manic episode may be unable to manage his finances because he will rapidly dissipate them, but his decision-making capacity will return as the episode ends. Subtle forms of decision-making incapacity can also arise from mildly altered mood states (depression, hopelessness, anxiety, euphoria), from cognitive dysfunction (impairment in memory or attention from head injury), or from personality traits (guilt, self-punishment, feelings of worthlessness).
COMPETENCE TO REFUSE PSYCHOTROPIC MEDICATION. In contrast to admission to a medical-surgical hospital, admission to a psychiatric hospital may be accomplished by voluntary or involuntary means. In either facility, however, there may be uncertainty about the patient's ability to consent to voluntary hospitalization. Patients who are demented or seriously depressed or psychotic often have difficulty understanding that they are ill, need treatment, or should be hospitalized. They may have difficulty comprehending the risks and benefits of treatment and hospitalization. Nevertheless, decisions about the person's ability to consent to voluntary hospitalization precede, and differ from, decisions about the person's ability, once hospitalized, to consent to treatment with medication.
Managing a person's refusal of psychotropic medication (e.g., antipsychotic or antidepressant medication), once he or she has been hospitalized, has been one of the most controversial issues in mental healthcare in recent years. Before the 1980s, many rejected the notion of a psychiatric patient's right to refuse medication, suggesting that the purpose of psychiatric hospitalization would be defeated if patients were permitted to refuse treatment with medication (Appelbaum, 1988). In part, the controversy about involuntary treatment of psychiatric inpatients with medication arose from the nature and effects of psychotropic medication. Psychotropic medications have been viewed somewhat inaccurately as powerful and dangerous substances whose use is akin to "mind control." Their risks, whether short-term dry mouth and constipation or long-term involuntary movement disorders, relative to their benefits, the treatment of the mental disorder, have been greatly exaggerated, at least by many attorneys and courts (Gutheil and Appelbaum).
Once patients enter psychiatric hospitals, especially on an involuntary basis by court order, they sometimes refuse recommended treatment with psychotropic medication, particularly antipsychotic medication. Patients refuse treatment based on problems in the physician-patient relationship, such as rebelliousness towards authority figures and realitybased side effects of medication (e.g., dry mouth, constipation, weight gain, restlessness), or most relevant in the present context, symptoms of the patient's illness, such as a delusional belief that the medication is poison. Decisions about hospitalizing a person involuntarily differ from those about medicating that person involuntarily once hospitalized; the former are largely a function of the person's future risk of violence to self or others due to a mental disorder, while the latter usually depend upon the person's ability to make decisions about accepting medication or his or her best interests. An involuntarily hospitalized patient, even one committed by a court, is not necessarily deemed unable to consent to medication. In most cases, a person who has been involuntarily hospitalized does not lose the legal right to object to or to refuse medication.
Voluntarily hospitalized patients who refuse medication for whatever reason may not be medicated involuntarily, except briefly in emergency situations. It is argued that patient autonomy regarding treatment refusal should be respected despite the consequences of continued illness, hospitalization, and incapacity. This legal right to refuse medication is based on the patient's right to free speech and thought, to freedom from bodily intrusion, the right to bodily integrity, a ban on cruel punishment, and the right to autonomy and self-determination.
Nevertheless, involuntarily hospitalized patients who refuse medication may sometimes be medicated involuntarily in nonemergency situations, as well as briefly in emergencies. Many states in the United States use a judicial model for these cases in which forced medication of involuntarily hospitalized patients may be accomplished only after a judicial hearing and court determination that the patient is incompetent to refuse the mediation because of the mental illness (Weiner and Wettstein). A substitute decision maker is sometimes appointed by the court to determine whether the patient should be compelled to take medication. This is the same procedure that would be followed if the physician sought involuntary surgery (e.g., amputation of a gangrenous extremity) on the patient. In contrast, in some U.S. states and in some Canadian provinces, the attending physician or a medical or administrative review panel decides whether or not to override the patient's refusal; the patient may then appeal the physician or panel's decision to involuntarily medicate to a court (Weiner and Wettstein; Ontario Ministry of Health). In England, the Mental Health Act of 1983 permits the treating physician to authorize medication for up to three months to an incompetently refusing, involuntarily hospitalized patient (section 56); after that, a second physician opinion is needed to continue the involuntary treatment (section 58) (Appelbaum, 1985). In this nonjudicial model, the patient's decision-making capacity about medication as assessed by the attending physician may still be the most important factor in the disposition of the case. However, the U.S. Supreme Court has held that decision-making capacity is not relevant to determining whether prisoners should be medicated involuntarily with psychotropic drugs (Washington v. Harper ).
According to empirical data about the right to refuse psychotropic medication, the judicial-review model, using a formal incompetence declaration, carries substantial fiscal costs, given the delays inherent in obtaining the required court hearing. It also involves prolonged periods of nontreatment pending the hearing, which often results in injuries to the patient, other patients, and staff (Ciccone et al.; Hoge et al.). Few courts ultimately grant the patient a right to refuse medication.
COMPETENCE FOR EXECUTION. According to U.S. law civil or criminal litigants must be legally competent before they can bring suit or have suit brought against them. In criminal law, defendants must be competent to stand trial, plead guilty, be sentenced, or be executed before those proceedings can occur.
Executing a person who is considered incompetent (i.e., "insane") at the time of execution, as opposed to at the time of the crime, has been ruled unconstitutional by the U.S. Supreme Court (Ford v. Wainwright ). Execution in such cases offends humanity, has no deterrent value to others, and offers no retribution to the condemned person. The courts, however, have yet to articulate a competence standard by which to adjudicate a death-row inmate as incompetent (Winick).
The courts have not yet decided whether, once deathrow inmates have been found incompetent, the state may involuntarily medicate them to restore competence and then execute them (Louisiana v. Perry ). Such an eventuality places the treating psychiatrist, who ethically must not participate in an execution, in a difficult dilemma: Medicate the inmate to relieve suffering, which leads to the inmate's death, or do not medicate the inmate, which spares the inmate's life but fails to reduce suffering (Heilbrun et al.). Only automatic commutation of an incompetent death-row inmate to life in prison would definitively resolve the matter.
Whether in healthcare, financial, legal, or any other area of decision making, the stakes for both persons and professionals in competence definitions are substantial. Identifying and labeling someone as incompetent can be stigmatizing and deprives the person of self-determination. Legal and healthcare delivery systems are then confronted with, and disrupted by, the need for surrogate decision making for the incapacitated or incompetent person. On the other hand, failure to protect the incapacitated person from making erroneous and harmful decisions (e.g., refusing necessary medical care) may not honor the person's best interests. The question then is when and how to respect people's choices and maximize their decision-making autonomy while protecting them from their own harmful choices (Drane). In most cases in the healthcare system, clinicians agree that the person should, or should not, be considered competent, even if there is no universal consensus on how much rationality and understanding are sufficient for the person to be considered legally competent and granted authority to decide for him or herself. Still, there are other cases in which judgments about the person's decision-making capacity are problematic, and clinicians, administrators, patients, families, and the courts become involved in emotionally charged disputes about how to manage the person's medical care. Such cases are unlikely to abate in the future as long as our society continues to value, and attempts to balance, autonomy and beneficence.
robert m. wettstein (1995)
SEE ALSO: Advance Directives and Advance Care Planning; Aging and the Aged: Healthcare and Research Issues; Autonomy; Informed Consent; Law and Bioethics; Mental Illness; Patients' Rights; Pediatrics, Adolescents; Professional-Patient Relationship; Research Policy: Subjects; Responsibility; Sexism; Surrogate Decision-Making
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Appelbaum, Paul S. 1988. "The Right to Refuse Treatment with Antipsychotic Medications: Retrospect and Prospect." American Journal of Psychiatry 145(4): 413–419.
Appelbaum, Paul S. 1998. "Ought We to Require Emotional Capacity as Part of Decisional Competence?" Kennedy Institute of Ethics Journal 8(4): 377–387.
Applebaum, Paul S. 1999. "Competence and Consent to Research: A Critique of the Recommendations of the National Bioethics Advisory Commission." Account Resolution 7(2–4): 265–276
Appelbaum, Paul S., and Grisso, Thomas. 1988. "Assessing Patients' Capacities to Consent to Treatment." New England Journal of Medicine 319(25): 1635–1638.
Beauchamp, Tom L. 1991. "Competence." In Competency: A Study of Informal Competency Determinations in Primary Care, pp. 49–78, ed. Mary Ann Gardell Cutter and Earl E. Shelp. Dordrecht, Netherlands: Kluwer.
Bonnie, Richard J. 1992. "The Competence of Criminal Defendants: A Theoretical Reformulation." Behavioral Sciences and the Law 10(3): 291–316.
Buchanan, Allen E., and Brock, Dan W. 1989. Deciding for Others: The Ethics of Surrogate Decision Making. Cambridge, Eng.: Cambridge University Press.
Buller, T. 2001. "Competence and Risk-Relativity." Bioethics 15(2): 93–109
Ciccone, J. Richard; Tokoli, John F.; Gift, Thomas E.; and Clements, Colleen D. 1993. "Medication Refusal and Judicial Activism: A Reexamination of the Effects of the Rivers Decision." Hospital and Community Psychiatry 44(4): 555–560.
Drane, James F. 1985. "The Many Faces of Competency." Hastings Center Report 15(2): 17–21.
Ford v. Wainwright. 477 U.S. 399 (1986).
Grisso, Thomas. 1986. Evaluating Competencies: Forensic Assessments and Instruments. New York: Plenum.
Grisso, Thomas, and Appelbaum, Paul S. 2000. Assessing Competence to Consent to Treatment: A Guide for Physicians and Other Health Professionals. New York: Oxford University Press.
Gutheil, Thomas G., and Appelbaum, Paul S. 1983. "'Mind Control, ' 'Synthetic Sanity, ' 'Artificial Competence, ' and Genuine Confusion: Legally Relevant Effects of Antipsychotic Medication." Hofstra Law Review 12: 77–120.
Gutheil, Thomas G., and Bursztajn, Harold. 1986. "Clinicians' Guidelines for Assessing and Presenting Subtle Forms of Patient Incompetence in Legal Settings." American Journal of Psychiatry 143(8): 1020–1023.
Heilbrun, Kirk; Radelet, Michael L.; and Dvoskin, Joel. 1992. "The Debate on Treating Individuals Incompetent for Execution." American Journal of Psychiatry 149(5): 596–605.
Hoge, Steven K.; Appelbaum, Paul S.; Lawlor, Ted; Beck, James C.; Litman, Robert; Greer, Alexander; Gutheil, Thomas G.; and Kaplan, Eric. 1990. "A Prospective, Multicenter Study of Patients' Refusal of Antipsychotic Medication." Archives of General Psychiatry 47(10): 949–956.
Louisiana v. Perry. 498 U.S. 38 (1990).
Morreim, E. Haavi. 1991. "Competence: At the Intersection of Law, Medicine, and Philosophy." In Competency: A Study of Informal Competency Determinations in Primary Care, pp. 93–125, ed. Mary Ann Gardell Cutter and Earl E. Shelp. Dordrecht, Netherlands: Kluwer.
National Bioethics Advisory Commission. 1998. Research Involving Persons with Mental Disorders That May Affect Decision Making Capacity Vol I: Report and Recommendations of the National Bioethics Advisory Committee. Rockville, MD: National Bioethics Advisory Commission.
Neu, Steven, and Kjellstrand, Carl M. 1986. "Stopping Long Term Dialysis: An Empirical Study of Withdrawal of Life Supporting Treatment." New England Journal of Medicine 314(1): 14–20.
Ontario Ministry of Health. 1987. Mental Health Act: Revised Statutes of Ontario. Toronto: Queen's Printer for Ontario.
Roth, Loren H.; Meisel, Alan; and Lidz, Charles W. 1977. "Tests of Competency to Consent to Treatment." American Journal of Psychiatry 134(3): 279–284.
U.S. President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research. 1982. Making Health Care Decisions: A Report on the Ethical and Legal Implications of Informed Consent in the Patient-Practitioner Relationship. Washington, D.C.: Author.
Washington v. Harper. 110 S. Ct. 1028 (1990).
Wear, Stephen. 1991. "Patient Freedom and Competence in Health Care." In Competency: A Study of Informal Competency Determinations in Primary Care, pp. 227–236, ed. Mary Ann Gardell Cutter and Earl E. Shelp. Dordrecht, Netherlands: Kluwer.
Weiner, Barbara A., and Wettstein, Robert M. 1993. Legal Issues in Mental Health Care. New York: Plenum.
Winick, Bruce J. 1992. "Competency to Be Executed: A Therapeutic Jurisprudence Perspective." Behavioral Sciences and the Law 10(3): 317–337.
com·pe·tence / ˈkämpətəns/ (also com·pe·ten·cy / -tənsē/ ) • n. 1. the ability to do something successfully or efficiently. ∎ the scope of a person's or group's knowledge or ability. ∎ a skill or ability. ∎ the legal authority of a court or other body to deal with a particular matter. ∎ the ability of a criminal defendant to stand trial, as gauged by their mental ability to understand the proceedings and to assist defense lawyers. ∎ (also linguistic or language competence) Linguistics a speaker’s subconscious, intuitive knowledge of the rules of their language. Often contrasted with performance. ∎ Biol. & Med. effective performance of the normal function. 2. dated an income large enough to live on, typically unearned.
1. The maximum size of rock particle transported by a particular flow of ice, water, or air. Ice has a high competence, because of its viscosity; flowing water has a lower competence, though this increases sharply as velocity increases. Wind has the least competence.
2. The relative rheological (see RHEOLOGY) properties of different rock types that are adjacent to one another. Typically, a competent rock is more viscous than an incompetent rock, more prone to fracture, and maintains its thickness on deformation. An incompetent rock is usually more ductile than a competent rock and therefore flows more easily.