From The Houston Chronicle:
Lawyers for Richard went to the U.S. Supreme Court asking the lethal injection be halted because of claims Richard was mentally retarded but justices rejected the appeal late Tuesday afternoon. Attorneys then filed late motions in state courts to try to stop the punishment and the execution was delayed beyond the 6 p.m. CDT time it could take place. The death warrant remained in effect until midnight.
The legal wrangling came following a Supreme Court decision earlier Tuesday to consider the constitutionality of lethal injection in a Kentucky case. Gov. Rick Perry’s office, however, said Richard’s execution should go forward as planned.