Rep. Aaron Schock made a rare court appearance on Wednesday as his legal team seeks to have charges against him dismissed.

Schock resigned in 2015 after his lavish spending was revealed, most famously having his office redecorated with a “Downton Abbey” theme. He was indicted the next year.

Schock’s legal team said prosecutors based the charges against him on ambiguous House of Representatives rules, The Associated Press reported.

“An ambiguous rule cannot be used to support the prosecution of a member of Congress,” Schock’s lawyer Benjamin Hatch argued, the Chicago Sun-Times reported.

Several courts have agreed the Constitution bars prosecutors, as members of the executive branch, from charging legislative branch members based on unclear congressional rules. the AP reported. Courts have ruled that they can be charged based on clear rules that require no interpretation.

Schock made an appearance at the hearing, but did not speak to the media.

Two of the judges on the three-judge panel asked whether members of Congress could write their own rules about paying taxes.

But Hatch said the rules were different from a violation of federal law and that it would be overreach for the courts to delve into gray areas.

“It would be the court fashioning a rule of Congress,” he said.

Prosecutors countered that the House rules would be introduced merely as evidence.

The indictment from 2016 said Schock broke various federal laws when he used campaign and federal cash to reimburse himself for car mileage he allegedly did not drive, stocks, and a charter flight to see the Chicago Bears play, among other expenses.

He is also accused of falsifying records and receipts in trying to cover up  questionable expenses and filing false income tax returns.

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