There have been some dark days in America in recent months, days when its astonished citizens have had reason to wonder whether its institutions and even its ideals — the Congress, the electoral process, the notion that honesty matters — had become too brittle to withstand what could seem like relentless assault.

Wednesday was not one of those days.

A federal judge in Manhattan sentenced Michael Cohen, Donald Trump’s former lawyer, to three years in prison over what the judge called a “veritable smorgasbord” of crimes, most important, paying hush money to two women who said they slept with his ex-boss. Those payments enabled Mr. Trump to conceal the accusations from voters in the closing weeks of the campaign. United States District Judge William Pauley said this violation of campaign finance laws created “insidious harm to our democratic institutions.” In so ruling, he demonstrated that those institutions have some life in them yet.

Mr. Trump has called the payments to the two women “a simple private transaction.” But prosecutors made clear that the payments were illegal campaign contributions because their purpose was to help win the election. This was reinforced shortly after Mr. Cohen’s sentencing, when federal prosecutors disclosed that, in a deal to avoid prosecution, the publisher of The National Enquirer admitted that, to help elect Mr. Trump president, and with his cooperation, it had paid $150,000 to buy the silence of one of the women, Karen McDougal, a former Playboy model who said she’d had a 10-month affair with Mr. Trump.

With prosecutors already having said in their sentencing memo for Mr. Cohen that “he acted in coordination with and at the direction of Individual-1" — that’s President Individual-1 to you — this is even more evidence they believe Mr. Trump conspired to commit a felony.