"Can you impeach someone who is no longer in office?"
First, set aside that Trump has already been impeached by the House. Yes, technically, the question is - can he be convicted.
My thoughts go to the Republicans and apparently at least one Democrat who will vote to acquit based on the logic that you can't impeach someone who is out of office. It would seem that as it stands there reasonable though twisted legal arguments from both sides. The Constitution does not speak to this circumstance.
"Republican senators and some legal scholars have said that Trump's impeachment trial in the Senate cannot proceed now that he is once again a private citizen. But many scholars have said that Trump's return to private life poses no impediment to an impeachment trial." -Yahoo News
So, here is my question.
I believe we have these institutions we called courts. And I believe, some of them are courts of appeal. And one of them, the Supreme one, makes all of its rulings based on what they interpret the constitution to allow or not.
Why not ask first before tying up the Senate with a potentially non-event?
Before going through all the machinations of a trial and with this glaring loophole for those senators seeking to duck and cover. Why not ask the Supreme Court to rule on whether or not a former President can indeed be tried in the Senate for high crimes and misdemeanors committed while in office but now out of office.
This gives the Senate time to consider the Biden appointments. And, it means, if the court says yes, the big dodge will be removed from any cowardly senator who wants to vote none of the above. If they say no, then move on, the court has spoken. Let's get those vaccines in arms, fix the bridges and save the polar bears.
Really, why not just ask first?