Sen. Robert Menendez has raised the legal stakes for all of Congress, and bought some crucial time for his own imperiled career, with the aggressive strategy he’s unveiled for fighting corruption charges.

If the New Jersey Democrat gets his way, then the indictment against him — alleging he put his congressional muscle to work for a longtime friend and benefactor in return for campaign cash and lavish pampering — will be put in limbo for years, maybe even until after he’s next up for re-election in 2018.

And in the end, Menendez indicated in several hundred pages of court filings this week, his ideal outcome is getting cleared without a trial but with the backing of the Supreme Court. His defense is looking for a landmark ruling that expands the range of congressional immunity from criminal prosecution.

It’s a high-risk approach, with consequences for every other current senator and House member and likely their successors as well. If Menendez wins, it will become much more difficult to prove malfeasance by lawmakers. But if he pursues his argument all the way to the ultimate appeal and then loses, the judicial precedent could make it easier to make federal criminal cases out of members’ questionable behavior.

At issue is the meaning of the Constitution’s provision that members of Congress “shall in all cases, except treason, felony and breach of the peace, be privileged from arrest during their attendance at the session of their respective houses, and in going to and from the same; and for any speech or debate in either house, they shall not be questioned in any other place.” The intended purpose of the so-called Speech or Debate Clause was to buttress the separation of powers, by preventing the president from using his law enforcement power to either coerce lawmakers to take his side or punish them if they didn’t.

The Supreme Court has refined the meaning of this language several times, generally to limit the extent of lawmaker immunity from prosecution. But the justices last tackled the clause 36 years ago, and since then lower federal courts have offered some inconsistent guidance about the breadth of the shield.

It’s those mixed messages in which lawyers for Menendez and his co-defendant, Florida eye surgeon Salomon Melgen, appear to see an opening now. They assert the Justice Department has no right to prosecute the senator for (or to compel his aides to testify about) his dealings with executive branch officials about a Medicare billing dispute involving Melgen and a port security contract from which the doctor stood to profit.

“The prosecution has no direct evidence (no witnesses, no recording, no letter, no email) that there ever was a quid pro quo agreement between Sen. Menendez and Dr. Melgen (because no such agreement ever occurred),” lawyers for the defendants said in papers filed Monday. “Instead, the prosecution wants to introduce Sen. Menendez’s legislative acts into evidence — something the speech or debate clause flatly precludes.”

The government is sure to counter that the Speech or Debate Clause is irrelevant in this case, and it appears to have a couple of Supreme Court precedents on its side. The justices ruled in 1972 that members and staff are not immune from prosecution for breaking criminal law in the course of doing their legislative business. And the court decided in 1979 that, while the clause protects actions clearly connected to the legislative process, perhaps including “calls to federal agencies seeking information, it does not protect attempts to influence the conduct of executive agencies.”

It may be up to Menendez, then, to persuade the courts that members of Congress should be given wide latitude to decide for themselves which of their own activities are part of their legislative or oversight responsibilities — and are thereby shielded from graft investigations.

“It still seems to me to be a long shot,” Michael Stern, a former senior member of the House general counsel’s office, has written about Menendez’s strategy in his “Point of Order” blog on congressional legal issues. But if the senator wins, Stern wrote, “this could significantly complicate any prosecution” of any member of Congress.

The opposite would be true if the Menendez case ends up at the Supreme Court and the justices decide to do the opposite of what he wants. If the court shrinks the gray area of congressional behavior that’s somewhat legislative, which would reduce the protections of the Speech or Debate Clause, that could make criminal investigations on the Hill much easier.

One reason the court might do so is to settle an issue that has become pretty muddled. Last month the court declined to consider the appeal of former Rep. Rick Renzi, an Arizona Republican facing three years in prison for public corruption, including promoting a federal land-swap bill a decade ago to reap a $700,000 payment. Renzi argued unsuccessfully (and with support from the House’s own bipartisan legal office) that evidence of his actions on the Hill should have been thrown out because of his speech or debate protection.

Seven years ago, however, the justices let stand a lower federal appeals court’s ruling that strengthened speech or debate protection, by declaring unconstitutional the FBI’s seizure of papers from the Rayburn office of Democratic Rep. William Jefferson of Louisiana. Even without that ill-gotten evidence, Jefferson lost his seat and went to jail for corruption, but the precedent about the raid was subsequently central to getting federal officials to drop potential prosecutions of at least three other House members.

Last summer, meanwhile, the House Ways and Means Committee declared itself “absolutely immune” under the Speech or Debate Clause from having to comply with Securities and Exchange Commission subpoenas as part of an investigation of alleged insider trading involving senior staffer Brian Sutter. (He’s since spun through the revolving door, and the SEC inquiry seems at a standstill.)

Four decades after the Constitution’s Article I, Section 6 was last considered by the highest court, Melgen and Menendez may be the ones to get it back on the docket. The process could keep the senator in office at least until he has chance to face the voters again. The result could be his salvation, or his final undoing.