Impeachment is a constitutional procedure that should be reserved only for extraordinary times with the most extreme examples of abuse of power by a president. That is why, in our country’s history, only two presidents have been impeached.

But this is one of those times.

The evidence of wrongdoing by President Trump is overwhelming. The impeachment inquiry has been conducted so far in a sober, responsible way. As Wednesday’s hearing made clear, the witnesses are credible and clear, and the story they tell is alarming. All members of Congress are now compelled to listen to the witnesses and independently determine whether the president’s conduct warrants impeachment.

Mr. Trump used the immense powers of the American presidency to pressure an ally to open investigations that would help him personally. That much is clear just from the call memo of the July 25 conversation between President Trump and President Volodymyr Zelensky of Ukraine. Any American who has not read the call memo should do so, because it is as shocking today to realize that Mr. Trump said the jaw-dropping phrase, “I would like you to do us a favor,” as it was the day it was released. He followed that by expressing his desire for Ukraine to investigate the 2016 election and the Bidens. That is sufficient in itself to prove unacceptable wrongdoing by the president.

But today’s testimony made clear that it goes much further. Two respected public servants — Ambassador William Taylor, an experienced diplomat and a decorated Vietnam War veteran, and Deputy Assistant Secretary of State George Kent, the State Department official overseeing European and Eurasian affairs — testified that the president and his personal attorney sought politically motivated investigations by the Ukrainian government into former Vice President Joseph Biden and allegations concerning the 2016 election (the latter references an unfounded conspiracy theory that Ukrainians, not Russians, were behind the hacking of the Democratic National Committee, and the Ukrainians framed the Russian government to make it look like that country was working with Mr. Trump’s presidential campaign ).