The phrase "false instrument" refers to a document or object that has been made to deceive someone by misleading them about its authenticity or purpose.
Cesar Martinez, 50 years old of New Rochelle, New York was arraigned on a felony complaint charging him with one count of Grand Larceny in the Third Degree, a class «D» Felony, one count of Grand Larceny in the Fourth Degree, a class «E» Felony and one count of Offering A False Instrument For Filing in the First Degree, a class «E» Felony. (newrochelletalk.com)
«It's a lot of underperforming buildings, where basically landlords want to take advantage of market forces and you have a lot of MCI abuses, vacancy bonus abuses, tenant harassment, and you have landlords who are filing a lot of false instruments in city agencies. (observer.com)
Hector Ramirez and Ana Cuevas (Ramirez's campaign manager in 2014), were indicted on seven counts for each allegedly false instrument submitted to The Board of Elections in the City of New York totaling 242 counts involving absentee ballots and applications for some 32 - 35 persons, some of whom were not eligible to vote. (thebronxchronicle.com)