President Donald Trump's personal attorney Rudy Giuliani on Tuesday told Congress he would not comply with a subpoena to hand over documents related to the House impeachment inquiry investigation into the White House's dealings with Ukraine—a move that critics noted could land him in jail.

"Giuliani and Trump must both think they're above the law," said CNN contributor Keith Boykin.

The president's lawyer was ordered on September 30 to hand over documents related to his efforts to pressure Ukrainian officials to open an investigation into Hunter Biden, the son of former Vice President Joe Biden, a frontrunner for the Democratic presidential nomination for the 2020 general election.

Giuliani did not reply to a request for comment but told ABC, "If they enforce it then we will see what happens."

By ignoring the subpoena, Giuliani is setting up yet another clash between the executive and legislative branches in the course of the inquiry. As Common Dreams reported, Trump announced on October 8 he would not cooperate with the inquiry, setting up a clear constitutional crisis.

Tuesday's refusal by Giuliani to comply with the subpoena appears certain to exacerbate the tension betweeen the two branches.

"Oh! I had no idea that law was optional," tweeted actress Lisa Ann Walter. "Good to know for when taxes or traffic tickets come up!"

Giuliani's lawyer, Jon Sale, wrote to Congress that the inquiry was "unconstitutional, baseless, and illegitimate."

"In addition," wrote Sale, "the subpoena is overbroad, unduly burdensome, and seeks documents beyond the scope of legitimate inquiry."

As journalist Judd Legum observed, Giuliani's behavior leaves the House with a clear enforcement option: arrest him.

Using its "inherent contempt" authority, Congress has the power to arrest and detain Giuliani right now. https://t.co/CSsaaBRPlt https://t.co/b6RETUTeyq pic.twitter.com/3RKOzgxCOv — Judd Legum (@JuddLegum) October 15, 2019

Scientist Kevin Fox opined on Twitter that if House Democrats don't deal with the president's lawyer now, they're risking future trouble.

"Giuliani is going to be the trial balloon for the backbone of the House," said Fox. "They'll need to hold him in inherent contempt and jail him or the rest of their subpoenas become impotent."