House Republicans have tapped leading conservative attorney Chuck Cooper to handle a lawsuit challenging the U.S. House of Representatives’ new rules on proxy voting, alleging the system is unconstitutional and dilutes the votes of members who are physically present in the chamber.

The lawsuit, filed in the U.S. District Court of the District of Columbia on Tuesday evening, alleges House members must be physically present in order to reach a quorum and then vote. Four constituents are also behind the complaint.