The Supreme Court has struck down Texas's widely replicated regulation of abortion clinics in the court's biggest abortion case in nearly a quarter of a century.

The justices voted 5-3 in favour of Texas clinics that had argued the regulations were a thinly veiled attempt to make it harder for women to get an abortion in the nation's second-most populous state.

Justice Stephen Breyer's majority opinion for the court held that the regulations are medically unnecessary and unconstitutionally limit a woman's right to an abortion.