His first term was marked by SEDCO's involvement in the largest oil blowout in history, the Ixtoc I oil spill, which caused extensive environmental damage. Clements faced heavily Democratic state legislatures during his tenure. In 1979, the legislature overrode one of his vetoes, the last time that Texas lawmakers have completed an override. In 1980, Clements commuted the death sentence of Randall Dale Adams to life in prison. Adams, the subject of "The Thin Blue Line", an Errol Morris documentary film, was exonerated in 1989 after serving twelve years in prison. Clements was also governor at the time of the execution of Carlos DeLuna, who was put to death in 1989; evidence questioning the findings of facts that underlay DeLuna's conviction was published in 2012.