It took nearly eight years for Congress to override a veto by President Barack Obama. It could hardly have chosen a worse measure on which to do so — or a more stark way of exposing its most craven impulses.

Obama was right to reject the Justice Against Sponsors of Terrorism Act, which would allow U.S. citizens to sue foreign nations for abetting terrorist acts, even if they are not included on the State Department’s official list of sponsor states. While the law names no names, it is obviously intended to allow the families of those killed in the Sept. 11 attacks to sue Saudi Arabia for its alleged involvement.

The problem is that law clearly violates the principle of sovereign immunity, which bars people from using their nation’s court system to sue a foreign government. If sovereign immunity is weakened, no country is more vulnerable than the U.S. In his veto message last week, Obama warned that the law undermines “longstanding principles that protect the United States, our forces, and our personnel.”

In addition, in cases brought by U.S. citizens, defense lawyers could potentially force Washington to release sensitive or even classified information. Saudi Arabia could also respond by canceling contracts with U.S. businesses and urging its Gulf Arab neighbors to reassess their cooperation with Washington on counterterrorism.

It’s not as if the Senate, which voted 97-1 to override, was unaware of these concerns. Sen. Bob Corker, the Republican chairman of the Foreign Relations Committee, said he had “tremendous concerns” about the law, while Democratic Sen. Dianne Feinstein confessed that the law is “the wrong thing to do.” Both of these senators, to repeat, voted in support of the legislation. All elected officials have made votes they regret, but rarely do they express their regrets on the same day as the vote.

Now 28 senators of both parties have issued a letter saying they hope to mitigate any negative consequences of the bill. Some cautious legislators had already added a provision allowing the administration to stay any suit so long as it is engaged in “good faith discussions” with the foreign state. On Wednesday, there was talk of limiting the law’s application solely to the Sept. 11 attacks or to Saudi Arabia.

Neither of these ameliorate the fact the U.S. Congress has undermined a fundamental tenet of international law. The only way to ensure U.S. soldiers, spies and diplomats remain protected is for Congress to repeal this measure it never should have passed.

Doing so may upset the Sept. 11 families, many of whom say the issue is not financial compensation but justice. Congress can better address their concerns by creating a new investigatory body, along the lines of the 9/11 Commission, to look into the narrower question of Saudi connections to the bombers. That would be far more helpful to the victims than making the U.S. a legal target for its enemies around the globe.