An open, manifest act from which criminality may be implied. An outward act done in pursuance and manifestation of an intent or design.
An overt act is essential to establish an attempt to commit a crime. It is also a key element in the crime of treason and has become a component of federal and some state criminal conspiracy laws. It also plays a role in the right of self-defense.
An attempt to commit a crime is an offense when an accused makes a substantial but unsuccessful effort to commit a crime. The elements of attempt include an intent to commit a crime, an apparent ability to complete the crime, and an overt act. An overt act is an act that is performed to execute the criminal intention and will naturally achieve that result unless prevented by some external cause. The act must directly move toward commission of the crime and must be more than acts of planning or preparation.
Defining when an act is more than preparatory has proved difficult. Several tests have been used to determine when an overt act has been committed. The "unequivocal" test states that a defendant's act, standing alone, is unequivocally consistent only with her or his intent to commit the allegedly attempted crime. This test has been criticized as too lenient on criminals because no act is truly unequivocal. A person who shoots someone several times can argue that she was only trying to injure the victim and that it was her skilled shooting and not luck that prevented the victim's death.
Some jurisdictions favor the "substantial act" test. They permit an attempt conviction when a defendant with the requisite criminal intent performs a substantial act towards the commission of the crime. Under this test, for example, a prospective burglar can be convicted of attempted burglary if apprehended in an alley with burglary tools, even though he had not determined which building he was going to burglarize.
The "probable desistence" test asks whether the defendant had gone so far down the road of crime that it is unlikely that she or he would have voluntarily desisted from completing the crime. One way of measuring this probability is to look at the past criminal record of an accused. Thus, an accused with a previous record may be convicted under this test, because her past propensity makes it unlikely that she would have stopped taking the acts leading to the crime.
The need for an overt act also is required in federal and some state criminal conspiracy prosecutions. A conspiracy is a voluntary agreement by two or more persons to commit an unlawful act or to use unlawful means to accomplish an act that is not in itself unlawful. Under federal law the overt act must be an independent act that comes after the agreement or conspiracy and is performed to effect the objective of the conspiracy. The overt act itself need not be a criminal act, because its sole function is to demonstrate that the conspiracy is operative. If, for example, two persons conspire to rob a bank and rent a getaway car, the rental is an overt act that in itself is perfectly legal. Some states, however, still adhere to the common-law rule that an overt act is not required to prove a conspiracy.
An overt act that justifies the exercise of the right of self-defense is one that causes a reasonable person to perceive a present intention to cause his or her death or great bodily harm.
The federal crime of treason contains an overt act requirement. Article III, Section 3, Clause 1, of the U.S. Constitution provides, "No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act." In such a case, an overt act means a step taken to execute a treasonable purpose, as distinguished from mere words or a treasonable sentiment, purpose, or design not resulting in action. It is an act in furtherance of the crime.