The first eight convictions for driving while intoxicated didn’t stop Donald Middleton of Houston from sliding behind the wheel and getting his ninth conviction.

This time, the judge had had enough.

When Mr. Middleton, 56, faced Judge Kathleen Hamilton of the 359th District Court in Texas on Tuesday, she sentenced him to life in prison. He won’t be eligible for parole for 30 years.

Such a harsh sentence is uncommon for drunken-driving convictions, which often lead to temporary license suspensions and prison stays that allow repeat offenders to return to the road. In Mr. Middleton’s case, he still had a valid driver’s license, despite the eight convictions.

Mr. Middleton’s case raises the question: How many times does someone have to be caught driving drunk before he or she can no longer legally drive?