Former Trump White House official Peter Navarro contended that Congress pushing him to testify violated the Constitution’s separation of powers. “The irony is that the Department of Justice itself has maintained a policy for more than 50 years that says that senior advisers like me absolutely cannot be compelled to testify before Congress‚” Mr. Navarro told Fox’s Sean Hannity on Friday. He continued‚ “Why? Because it violates the constitutional separation of powers and interferes with the...