In dissent, Justice Stephen Breyer (news - web sites) said the Ewing case is a rare example of a sentence that is so out of proportion to the crime that it is unconstitutional. He was joined by Justices John Paul Stevens (news - web sites), David Souter (news - web sites) and Ruth Bader Ginsburg (news - web sites).
Outside California's three-stikes law, a 25-year prison term is more the norm for someone convicted of first-degree murder, not shoplifting, Breyer wrote.
"Ewing's sentence is, at a minimum, two to three times the length of sentences that other jurisdictions would impose in similar circumstances," he wrote.
Breyer read a summary of his dissent from the bench, a step justices usually reserve for cases in which there is strong, often ideological, disagreement.
At least 7,000 people have been sentenced under the California law, including more than 300 such as Ewing and Leandro Andrade, the men at the heart of Wednesday's cases. Both received long sentences when the courts treated a relatively minor crime as a third-strike felony.