It's frustrating that nobody pushes the issue. I get that as a Constitutional matter he can always plead the fifth -- implicitly admitting that he did something illegal and that telling the truth about his actions would incriminate him. That's fine. But he should be forced to make that plea, rather than being allowed to simply decline an invitation. And that goes back to the Mueller "investigation," at least. It's utterly fucking insane that Mueller was tasks with looking into Trump campaign complicity with Russia's election interference, and he couldn't be bothered to even try to make the main conspirator answer a single question under oath. Everyone acts like it's a national priority to make sure Trump never has to testify under oath, or even to plead the fifth. I get why his lawyer is trying to protect him from himself, but why are others doing so?
It's not like this is normal. Like even when it's something utterly trivial, like Hillary Clinton's decision to use a private email server for work, we have sworn testimony in front of Congress. Even Ronald Reagan testified about the Iran/Contra criminal conspiracy (even if he mostly just answered "I can't recall.") But Trump is treated as if he were a king, who had to be regarded as inherently immune to questioning.
It is frustrating. Both Clintons were called before congress and testified. The difference is, neither had anything to hide, they did nothing wrong, but that didn't stop the Republican Taliban from trying to dig up dirt.
I know Bill was impeached, but what he was impeached for had nothing to do with how he governed. Also, he was acquitted.
Finally, a congressional hearing is not like a courtroom proceeding. I know you're under oath, but I don't think you can take the 5th. All you can do what Bill Barr did and just pretend you don't understand the questions.