Citing use of executive privilege to withhold information from Congress, using end runs around Congress on issues of immigration and appointment and violating religious freedom, Congressional Republicans and constitutional experts said President Barack Obama has abused his power.

“President Obama has treated the Constitution’s separation of powers as if it were a matter of convenience that may be ignored when it gets in his way,” Sen. Mike Lee (R-Utah), a former constitutional attorney and Supreme Court clerk, said in his testimony to the House Judiciary Committee Wednesday.

“Rather than cooperating with Congress or respecting the Constitution’s separation of powers, he has in many instances chosen to go it alone and in the process has exceeded the proper bounds of executive power,” he said.