A Louisiana congressman accused of taking bribes challenged his indictment before a federal appeals court Wednesday, claiming grand jury testimony infringed on his constitutionally protected activities.

Democratic U.S. Rep. William Jefferson's attorney told a three-judge panel of the 4th U.S. Circuit Court of Appeals that a congressional aide's testimony about Jefferson's leadership in passing trade legislation benefiting African nations violated the Constitution's speech or debate clause.

The clause says congressmen "shall not be questioned in any other Place" for speech or debate associated with their legislative actions. A federal judge in February refused to dismiss the indictment. Jefferson, who faces up to 235 years in prison if convicted of bribery and other charges, appealed.

Assistant U.S. Attorney Mark Lytle told the appeals court judges that U.S. District Judge T.S. Ellis III got it right when he ruled that Jefferson's lawyers sought to apply the clause so broadly that it would make it virtually impossible to ever charge a congressman with a crime.

Jefferson's attorney, Robert P. Trout, contended the testimony about how the congressman gained influence with African leaders was at the heart of the government's case. Trout said one of the ways Jefferson gained that influence, according to grand jury testimony, was through leadership on the trade legislation.

The appeals court judges vigorously questioned Lytle and Trout for about 50 minutes, focusing on whether the indictment was tainted if prosecutors neither sought nor relied on the testimony cited by Jefferson.

Lytle said the aide volunteered the information in question, which amounted to just four lines in a massive set of grand jury transcripts.