A federal judge heard arguments Friday in a closely watched dispute between Georgia’s Fulton County and the Trump administration over whether the FBI must return thousands of 2020 election ballots seized during a January search warrant execution, as both sides sharply clashed over the scope of an ongoing federal investigation.

The hearing before U.S. District Judge J.P. Boulee, an appointee of President Donald Trump, came after court-ordered mediation failed and followed a procedural win for the administration a day earlier, when the judge blocked Fulton County’s attempt to compel testimony from the FBI agent who justified the search warrant in a written affidavit.