So tonight I decided to do some poking around to see if this word had been used in earlier cases. And as near as I can tell, it hasn't. I mainly poked around in Nexis (along with some follow-up Google searches). It's not only difficult to prove a negative but it's also hard to know whether you're using just the right search words to bring up all the right examples. But the cases I'm familiar with are the trials/hearings for James Traficant (2002), Newt Gingrich (1997) and Jim Wright (1989). And I've been able to find few if any cases where reports at the time referred to these as 'trials' as opposed to 'hearings.'
This lengthy explainer article at CQ-Roll Call goes into great depth about the history and procedures of the Ethics Committees. And the word 'trial' isn't used once in the whole thing.
Calling it a 'trial' seems new.
The same seems to be the case in the Senate, though that's another chamber. So possibly different terms would apply.
At some level, it's a semantic distinction. If you want to call it a trial, you can. I'm also not trying to call out the rest of the press because we've been calling it a 'trial' too.
But here's the thing. Is there some reason this is being referred to as a 'trial' whereas these proceedings seem to have been referred to in the past as 'hearings'? It's quite possible I have not looked closely enough yet. Or perhaps the Committee's own rules or vocabulary has changed since 2002. Perhaps they've called for a slightly different kind of proceeding.
For now, I'm still trying to get to the bottom of this. If you're familiar with this and can point me to one of those possibilities in the paragraph above or perhaps just show me examples I've missed, I'd really appreciate it.