As House managers make their impeachment case, many Americans will dismiss it all as a partisan effort that hasn’t persuaded the country and will die in the Senate. They have a point. But the precedents that Democrats are setting could live on, so forgive us if we explain how dangerous the House’s impeachment logic is to future Presidents and the Constitution’s separation of powers.

Especially pernicious is the new House “corrupt purposes” standard for removing a President from office. The House managers don’t assert that any specific action by President Trump was an abuse of power or a violation of law. They don’t deny he can delay aid to a foreign country or ask a foreign leader to investigate corruption. Presidents do that all the time. Instead they assert in their first impeachment article that Mr. Trump is guilty of “abuse of power” because he committed those acts for “corrupt purposes.”

As an aside here, we should repeat that a President doesn’t have to break a specific law to commit an impeachable offense. Mr. Trump’s lawyers are wrong on this point. Presidents were accused of breaking specific laws in America’s three previous impeachments. But under the Constitution a President can commit “high crimes and misdemeanors” if he commits non-criminal acts that exceed his executive authority or if he refuses to execute the law.

But this means committing specific acts that are impeachable in and of themselves. Examples might be deploying U.S. troops against political opponents, or suspending habeas corpus without Congressional assent. (Lincoln received a Congressional pass in wartime.)

House Democrats are going much further and declaring that Mr. Trump’s acts are impeachable because he did them for “personal political benefit.” He isn’t accused of corruption per se. His Ukraine interventions are said to be corrupt because he intended them to help him win re-election this year. In other words, his actions were impeachable only because his motives were self-serving.