Final answer:
The False Claims Act is the piece of legislation that penalizes federal contractors for filing fraudulent claims to defraud the US government.
Step-by-step explanation:
The piece of legislation that penalizes federal contractors who knowingly file false or fraudulent claims in order to defraud the US government is the False Claims Act. This law is designed to protect the government from being overcharged or sold substandard goods or services.
The False Claims Act imposes liability on persons and companies who defraud governmental programs and includes a qui tam provision that allows people who are not affiliated with the government to file actions on behalf of the government.