Menendez Lashed Out on the Senate Floor. Now, He’s Fighting Back in Court.

Lawyers for Senator Robert Menendez, a New Jersey Democrat charged with accepting cash and gold bribes, asked a judge on Wednesday to dismiss the indictment, saying overzealous prosecutors were criminalizing normal legislative activity and flouting constitutional protections afforded to members of Congress.

The arguments, contained in the first legal brief filed by Mr. Menendez’s defense team, provided an early glimpse into his legal strategy four months before he is scheduled to stand trial in Manhattan on federal corruption charges.

The brief came a day after Mr. Menendez, 70, stood on the Senate floor to offer a highly unusual rebuttal to the charges outlined in three successive indictments. Prosecutors have accused him of acting as an unregistered agent of Egypt, taking bribes to help the government of Qatar, exchanging political favors for bricks of gold and trying to halt criminal investigations to help allies in New Jersey — all points that his lawyers addressed in the 42-page filing.

“The government’s accusations in this case — that he sold his office and even sold out his nation — are outrageously false, and indeed distort reality,” Mr. Menendez’s lawyers wrote. “Every official act the senator took represented his good-faith policy judgments.”

The timing of the filing appears to have been no coincidence. Legal motions were not due until Jan. 15, and the lawyers, in breaking months of silence a day after the senator defiantly addressed the charges in Washington, signaled a shift in both strategy and tone.

In a statement, Adam Fee, a lawyer for Mr. Menendez, said the senator should not even face a trial.

“The government should be forced to end this case,” Mr. Fee said, “as well as its one-sided effort to falsely tarnish the reputation that Senator Menendez built through 50 years of patriotic public service.”

In arguing that the judge, Sidney H. Stein of Federal District Court, should dismiss the indictment, Mr. Menendez’s lawyers relied on two legal principles.

They cited a 2016 Supreme Court decision that overturned the conviction of Bob McDonnell, a former Republican governor of Virginia, to claim that many of the senator’s actions were not “official acts” and therefore were not illegal; the McDonnell ruling made it harder to prosecute public officials by narrowing the kinds of quid-pro-quo actions that could be defined as corruption.

Other conduct, Mr. Menendez’s lawyers said, was protected because of legislative independence embedded in the Constitution’s “speech or debate clause.”

The lawyers also accused the government of making belated disclosures of critical discovery materials, hiding “key exculpatory evidence from the public’s and the court’s view” and using evidence to present a “distorted reality.”

They said prosecutors relied on “made-for-tabloid images of cash and gold bars” in place of “actual evidence of a bribery scheme” to manufacture a narrative based on “speculation, cherry-picking and innuendo.”

The U.S. attorney’s office in Manhattan will have the opportunity to respond to the defense’s arguments when prosecutors file their legal briefs in the case, which are due by Feb. 5.

Nicholas Biase, a spokesman for the U.S. attorney’s office in Manhattan, declined to comment on the new filing.

Mr. Menendez and his wife, Nadine Menendez, were first indicted in September on charges they took hundreds of thousands of dollars in bribes, including bars of gold bullion, in exchange for the senator’s willingness to use his political influence at home and abroad. Investigators seized 13 gold bars, $566,000 in cash and a 2019 Mercedes-Benz during June 2022 searches of Mr. Menendez’s home in Englewood Cliffs, N.J., and a safe deposit box. Three New Jersey businessmen were also charged in the bribery scheme.

Prosecutors said the car had been given to Ms. Menendez as part of the scheme to replace a vehicle that police records show she was driving when she struck and killed a pedestrian, Richard Koop, 49, in Bogota, N.J.

Then, in mid-October, prosecutors added a new charge: that Mr. Menendez conspired to act as an agent of Egypt even as he was serving as the chairman of the Senate Foreign Relations Committee.

A third indictment, released last week, accused him of using his political influence to benefit the government of Qatar.

All five defendants, who are each represented by separate lawyers, have pleaded not guilty to the charges.

In Tuesday’s speech on the Senate floor, Mr. Menendez accused prosecutors of abusing the grand jury process by dribbling out new charges and details in successive indictments, a strategy he said was designed to taint the jury pool.

“I’m innocent,” Mr. Menendez said in his speech, “and I intend to prove my innocence.”