The Daily Caller reports that Congresscritter Keith Ellison has noted that a Democrat-controlled House of Representatives could impeach a Republican-appointed Supreme Court justice. He’s correct. A handful of federal judges have been impeached by the House, and some convicted by the Senate.
Indeed, the Democrats could use one of their members as an expert to guide such a process. Before being elected to Congress, Rep. Alcee Hastings was impeached, convicted, and removed from his office as a U. S. District Judge.
There’s a growing group among the Democrats in Congress agitating for the impeachment of President Trump. It may be that they are just throwing some political mud around as a form of self-promotion. OTOH, they may really believe that Trump should go. If the later is the case, they need to get themselves better organized. Not all of them were around for the Clinton impeachment 19 years ago, so they should pick a leader with some actual practical experience with the impeachment process. Alcee Hastings comes to mind.