Does a target of an investigation have the right to smear a witness who might or who did testify against him, and then claim he has free speech right to so engage?  Does he have the right to threaten removal from employment or position to limit any future witness from providing testimony when subpoenaed by Congress?

Trump tweeted this weekend slamming Jennifer Williams,  calling her a Never Trumper.   Williams testifies today. So the most powerful man in the world claims he has the right to tweet and disparage to tens of millions of people, intimidating that or any future witness who is compelled to testify against him?   He is asserting that anybody who agrees to a subpoena should now be labelled “Never Trumpers” without providing one iota bit of evidence.