The governor's brief tells the state's Supreme Court that the Texas Constitution only grants him the power to grant clemency.

Gov. Greg Abbott is urging the Texas Supreme Court to block Robert Roberson from testifying before a House panel Monday, arguing lawmakers in the committee are effectively usurping state clemency power left solely to him by subpoenaing the death row inmate.

It’s rare for governors to step in to halt executions. In the case of Robert Roberson, it ended up being state lawmakers who took extraordinary steps.