Under Poynings' Law (1494), as it had been operationalized since the seventeenth century, legislation initiated by the Irish parliament was transmitted in draft form ("head of bills") to the privy council in England. The council might reject such a draft altogether, or it might return it to the Irish parliament either as received or with amendments. If the bill was returned, the Irish parliament could only accept or reject it with whatever amendments had been made. Yelverton's Act, enacted with government support in a quasi-revolutionary situation, eliminated this frustrating mechanism and initiated an era of "legislative independence." Although the English privy council retained the power to withhold the royal assent, it used this powercautiously during the remaining eighteen years until the Act of Union rendered the issue moot.
AN ACT TO REGULATE THE MANNER OF PASSING BILLS, AND TO PREVENT DELAYS IN SUMMONING OF PARLIAMENTS
Whereas it be expedient to regulate the manner of passing bills in this kingdom, be it enacted . . . that the lord lieutenant, or other chief governor or governors and council of this kingdom for the time being, do and shall certify all such bills, and none other, as both houses of parliament shall judge expedient to be enacted in this kingdom, to his majesty his heirs and successors, under the great seal of his majesty his heirs and successors, under the great seal of this kingdom without addition, diminution, or alteration.
II. And be it further enacted . . . that all such bills as shall be so certified to his majesty, his heirs and successors, under the great seal of this kingdom, and returned into the same under the great seal of Great Britain, without addition, diminution, or alteration, and none other shall pass in the parliament of this kingdom; any former law, statute, or usage to the contrary thereof in anywise notwithstanding.
III. And be it further enacted, that no bill shall be certified into Great Britain, as a cause or consideration for holding a parliament in this kingdom, but that parliaments may be holden in this kingdom, although no such bill shall have been certified previous to the meeting thereof.
IV. Provided always, that no parliament shall be holden in this kingdom until a licence for that purpose shall be first had and obtained from his majesty, his heirs and successors, under the great seal of Great Britain.
Statutes at Large Passed in the Parliaments Held in Ireland, 1310–1800 (1786–1801), vol. 12, pp. 356.