McDonnell Douglas Corp., targeted in a "whistleblower" lawsuit accusing it of overcharging the government by about $175 million, argued Monday that the law authorizing such lawsuits must be struck down.

Lawyers for the aerospace company asked U.S. District Judge William Keller to declare unconstitutional a recent addition to the 126-year-old False Claims Act. The judge took the matter under advisement and gave no indication of when he would rule.McDonnell Douglas is challenging a 1986 amendment to the law permitting private citizens to sue for fraud perpetrated on the government. Under that law, the Justice Department examines the complaint and may decide to take over the prosecution. If successful, the "whistleblower" can receive a portion of the damages.