What is To Falsify?

Legal Definition
Crim. law. To prove a thing to be false; as, " to falsify a record." Tech. Dict.; Co. Litt. 104 b. To alter or make false a record. This is punishable at common law. Vide Forgery.

2. By the Act of Congress of April 30, 1790, s. 15, 1 Story's L. U. S. 86, it is enacted, that if any person shall feloniously steal, take away, alter, falsify, or otherwise avoid, any record, writ, process, or other proceedings in any of the courts of the United States, by means whereof any judgment shall be reversed, made void, or not take effect; or if any person shall acknowledge, or procure to be acknowledged, in any of the courts. aforesaid, any recognizance, bail, or judgment, in the name or names of any other person or persons not privy or consenting to the same, every such person, or persons, on conviction thereof, shall be fined not exceeding five thousand dollars, or be imprisoned not exceeding seven years, and be whipped not exceeding thirty-nine stripes'. Provided nevertheless, that this act shall not extend to the acknowledgment of any judgment or judgments by any attorney or attorneys, duly admitted, for any person or persons against whom any such judgment or judgments shall be had or given.
-- Bouviers Law Dictionary
Legal Definition
Chancery practice. When a bill to open an account has been filed, the plaintiff is sometimes allowed to surcharge and falsify such account; and if any thing has been inserted that is a wrong charge, he is at liberty to show it, and that is a falsification. 2 Ves. 565; 11 Wheat. 237. See Account stated; Surcharge.
-- Bouviers Law Dictionary