In light of a potential Trump impeachment, if there’s anything lawmakers have learned, it’s that impeachment is unpredictable.

No US president has ever been removed from office through impeachment

Democrats must learn that trying to impeach President Donald Trump will not be easy, nor a slam dunk – it has never been easy to impeach a sitting president.

No US president has been removed from office by impeachment and conviction. Only two presidents in US history have been impeached: Andrew Johnson and Bill Clinton, who were both later acquitted by the Senate.

President Richard Nixon resigned from office before he could be impeached.

Why impeachment is unpredictable

The key to predictability in impeachment is known quantities. In other words, one has to be certain they have their hands on the proverbial smoking gun.

What’s problematic in impeachment inquiries are unknown quantities: Having to deal with new information one wasn’t prepared for; someone or something that could arise that discredits the testimony of crucial witnesses.

In the end, as it always does in legal matters, it comes down to what you can prove.

Republicans are frustrated, and rightly so, because they have been prevented by Democrats from seeing key pieces of evidence. They have complained that committee chairman Adam Schiff is playing judge, jury and executioner.

What is predictable so far about Trump’s impeachment

Democrats in the House hoping to impeach President Donald Trump need to take a look back into the past at previous impeachment efforts and the lessons they may provide.

Lesson number one is that successful impeachment requires a bipartisan coalition. The move by Democrats to impeach Donald Trump has zero Republican support. In fact, Republicans across the board believe that President Donald Trump did absolutely nothing wrong in his dealings with Ukraine.

Currently, Republicans are unified against the impeachment of President Donald Trump.