A federal appeals court appeared skeptical on Thursday of the justice department’s interpretation of US Congress members’ immunity from criminal investigations and whether it allowed federal prosecutors to access House Republican Scott Perry’s phone contents in the January 6 investigation.

The department seized Perry’s phone in the criminal investigation last year and was granted access to its contents by a lower court, until Perry appealed the decision on the grounds that the speech or debate clause protections barred prosecutors from seeing his messages.

Two of the three DC circuit judges appeared unconvinced about the justice department’s reading of the clause – the constitutional provision that shields congressional officials from legal proceedings – though it was unclear whether that would lead to them ruling against prosecutors.

The court did not issue a ruling from the bench during the partly unsealed hearing, but the judge’s decision could have far-reaching implications for witnesses like Perry and even Mike Pence in the January 6 investigation, as well as the constitutional power and scope of the protection itself.

The two Trump-appointed judges, Gregory Katsas and Neomi Rao, indicated they could rule in two ways: that messages with people outside Congress are not confidential at all, or that Perry could not be prosecuted or questioned about the messages, but that prosecutors could gain access to them.

The supreme court has ruled in several instances on the speech or debate clause. While the exact nature of the protection remains vague, it has generally found the protection to be “absolute” as long as the conduct came in furtherance of legislative activity.

At issue is whether Perry’s communications with third parties as he sought to assist Trump’s efforts to overturn the 2020 election results – and in particular, “informal” fact-finding – could be classified as legislative activity that would fall under the speech or debate clause.

Perry’s main lawyer, John Rowley, argued that the congressman was protected from being forced to give up roughly 2,200 messages on his phone to prosecutors because they amounted to legislative work as he prepared for the 6 January certification and possible election reform legislation.

But the justice department’s lawyer John Pellettieri disputed Rowley’s broad reading of the clause and argued that such “informal” fact-finding that had not been authorized by Congress as an institution meant Perry was acting unilaterally and therefore beyond the scope of the protection.

Katsas and Rao sharply quizzed the justice department on its position that only committee-authorized investigations were protected under the speech or debate clause, and how any other fact-finding could not be a legislative activity.

Katsas ran the department through various scenarios, including whether a recording of a call made by a member of Congress to a third party that they would use to inform how they voted on specific legislation would be protected – to which the department replied that it would not.

“So a member who is not on a committee has no fact-finding ability?” Rao asked.

Katsas added that he found it “odd” that “a member working to educate himself or herself” on how to vote would not be covered by the protection.

The justice department argued in response that the conduct had to be “integral” to actual “legislative procedures” to be protected, and warned that the speech or debate clause would otherwise include anything members of Congress did so long as they claimed it was legislative work.

The department also suggested that the conduct had to be “bona fide” legislative work – which prompted a response from Katsas that judges were not supposed to consider the motive and the behind-the-scenes decision-making of members of Congress.

At the end of the hearing, Perry’s lawyer Rowley added that the department’s narrow interpretation of the speech or debate clause – that it had to be authorized and integral to actual legislative procedure – would mean the minority in Congress would have no protection in researching legislation.

The hearing also revealed the previously sealed ruling by the chief US judge for the District of Columbia, Beryl Howell, in December that Perry was appealing: Howell had decided that Perry’s fact-finding messages were not protected because they were not part of a formal congressional investigation.