The justices are weighing an appeal of a much-disputed ruling by the 9th Circuit Court of Appeals that held last year that it was cruel and unusual punishment to enforce criminal laws against homeless people who are living on the street if a city doesn't offer enough shelters as an alternative.

The appeals court's opinion quoted Anatole France's famous comment that "the law, in all its majestic equality, forbids the rich and poor alike to sleep under bridges," and from there, it announced a principle of human rights to strike down city laws that "criminalize the simple act of sleeping outside on public property."

As precedent, Judge Marsha Berzon cited parts of a 1968 Supreme Court opinion in which several justices questioned whether "chronic alcoholics" may be punished for being drunk in public if they cannot control themselves.