Rep. Tom Tiffany, R-Wis., sparked outrage from Democrats on Thursday when he used a hearing on the Bureau of Alcohol, Tobacco, Firearms and Explosives to ask why Hunter Biden had not been charged with allegedly lying on a gun transaction form.

At a hearing titled "ATF’s Assault on the Second Amendment: When is Enough Enough?," Tiffany asked Rob Wilcox, Senior Director of Policy for Everytown for Gun Safety, about an incident related to a firearm purchase by President Biden’s son in 2018.

"If a person lies on ATF Form 4473 and is a user of unlawful drugs, you can get between five and 10 years for that. Is that correct? Is that your understanding?," he asked.

Wilcox corrected Tiffany to say that the sentence was now up to 15 years.

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Hunter Biden gets off plane with president

President Biden and his son, Hunter Biden, step off Air Force One at Hancock Field Air National Guard Base in Syracuse, N.Y., on Feb. 4, 2023. (AP Photo/Patrick Semansky)

"Why hasn't Hunter Biden been prosecuted for the crime that he committed?" Tiffany said, sparking noise from the hearing room.

"I'm not aware of the facts of that case and can't comment on it," Wilcox responded. 

"Who do we talk to to see why this case is not being prosecuted? He said very clearly in his book that he used drugs," Tiffany replied.

The incident to which Tiffany referred relates to one in which a gun owned by Biden was thrown in a trash can outside a market in Delaware. A firearm transaction report indicated that Biden purchased a gun earlier that month.

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On the firearm transaction report, Biden answered in the negative to a question that asked if he was "an unlawful user of, or addicted to, marijuana or any depressant, stimulant, narcotic drug, or any other controlled substance?"

However, Biden was discharged from the Navy in 2014 after testing positive for cocaine. Biden would later write a book about his issues with drugs and addiction.

Tiffany’s question brought pushback from at least one Democrat who called a point of order, saying it was not "totally irrelevant" to the hearing. Tiffany laughed off the objection.

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"I understand why you do not want Mr. Wilcox to answer that question," he said. "Because there's a dual system of justice in America. That's what's going on right now. And everybody's talking about it across America. There’s two standards of justice that are going on."