Valid sources have been in the news all the while it happened. Where and what were you watching and reading? It's in the public sphere comprised of records, videos, testimony, investigations, statements from Rump himself and his administration.
Google is your friend here as I'm not going to bother to link any of it to you simply because you'll refuse to read it. It's easy-peasy to look up.
And yes, they investigated the fat orange ogre for more than two years, impeached him twice and yet the GOP controlled senate refused to sentence him, saying he should be tried after he left office. You did see that much, didn't you?
Oh, and don't forget, Barr squashed about half a dozen investigations into Rump, intentionally misrepresented the findings of the Mueller report, and then wouldn't release it for a over a month until the dust settled. When examined by everyone, he lied his fat ass off about the contents of the report.
Turns out he did the same thing with the Iran-Contra affair, witholding 1,700 pages of intell from Congress, protecting the Bush administration . Years later, when the facts were released, it showed he lied his ass off then as well.
As for rule of law, no one comes across the border willy-nilly. They're caught, rounded up, lots are immediately deported, and those who have a valid claim have their day in court.
All the best,
Nonoise
