W

ednesday was a sad day for America, a tragic bookend to an era of presidential accountability that began with the Watergate scandal. For a relatively brief period in American history, presidents had to follow the law, respecting the independence of the Justice Department and heeding the oversight demands of Congress. The cautionary example of President Richard Nixon, as journalist Bob Woodward once wrote, cast a “shadow’’ over each of his successors.

When Chief Justice John Roberts gaveled President Trump’s trial to a close, he gaveled that era to a close too. In declining to hold a true trial with relevant witnesses, despite ample evidence of misconduct, and in failing to remove President Trump from office, the Senate made clear that neither he nor future presidents need fear any constitutional consequences if they violate the law, put personal gain over the national interest, corrupt their office, or obstruct Congress.

Presidents were already immune from criminal prosecution under a theory embraced by the Justice Department. Now they needn’t fear Congress either. The only remaining check is the electorate — which, the Senate has now decided, the president is free to enlist foreign countries to manipulate.

If there is a bright spot in this verdict, it’s the courage of former Massachusetts governor and current Utah senator Mitt Romney, the 2012 Republican presidential nominee. He was the lone Republican to vote guilty, marking the first time in American history that any senator has voted to remove a president of his own party. Romney’s vote deprives the president of the ability to claim that his impeachment was purely a partisan witch hunt, and puts a significant asterisk next to his acquittal. It was a demonstration of a disturbingly rare practice in today’s national politics: breaking from one’s party not just for the sake of reelection but for the sake of principle.

Perhaps the fact that at least one Republican voted to remove Trump will serve as some deterrent against future presidential misconduct. But it is no substitute for the guilty verdict that Trump clearly deserved. Trump was impeached for a crystal clear abuse of power and obstruction of justice. He corruptly withheld $391 million in military aid from Ukraine to pressure its leader into announcing investigations into Trump’s political opponents and then stonewalled Congress when it began investigating. The president’s defenders did not mount any serious factual defense against either charge. They simply demanded the Senate acquit him — which it did.

It is not the first time the Senate has lowered the standards of acceptable presidential conduct by declining to remove an impeached president. But it is by far the most troubling precedent. The acquittal of President Clinton in 1999 arguably set the precedent that presidents could lie about personal matters without losing their job. The acquittal of President Trump says presidents can ignore congressional subpoenas, use the power of the office to help themselves, and barter official actions for personal favors. It also says that future presidents can do virtually anything they want to secure reelection.

That is the country that 52 senators chose to leave to their children. It could take years for the damage from that choice to come fully into focus. Or maybe we’ll know sooner: Trump himself is certain to use the carte blanche the Senate just gave him. The kind of corrupt, self-serving leadership that American diplomats used to criticize in other countries is now ensconced in the White House and blessed by the Senate.

At least the trial, thanks to the masterful work of the House Democratic impeachment managers, put the facts squarely in front of the American people. Even some Senate Republicans conceded that Trump did what he was accused of. Voters who paid attention will have a good sense of Trump’s actions when they decide in November whether to reelect him.

But it should not have come to that. The Constitution gave the impeachment power to Congress to protect Americans from a corrupt president, and this Senate ducked the responsibility entrusted in it.

After President Nixon resigned under the threat of impeachment, this is how the Globe editorialized:

“Congress is embarking on a new course. . . . It has, we think, a new awareness of its powers and importance. And the people, thanks to the televised proceedings of a few weeks ago, have a new and justified respect for its members. From now on the Congress should abandon the submissiveness of its less than recent past and not be afraid to assert itself. That would be healthy for our system of checks and balances.’’

And indeed, for almost 50 years, it did assert itself. Our system of checks and balances was healthier.

But this Senate has embarked on a new course, too, restoring the submissiveness of the pre-Watergate era and leaving future generations to pay the price.

Editorials represent the views of the Boston Globe Editorial Board. Follow us on Twitter at @GlobeOpinion.