In the wake of the Nov. 13 terrorist attacks in Paris, governors in Texas and a number of other states have said they will not accept refugees from Syria, but legal experts question whether they can shut the doors of their states to the refugees.

In a letter to President Barack Obama on Nov. 16, Texas Gov. Greg Abbott also urged Obama, because of “the deadly terrorist attack in Paris,” to back off from plans to accept more Syrian refugees in the United States.

Abbott wrote that the federal government does not have background information necessary to conduct proper security checks on the Syrians.