SAN FRANCISCO (Reuters) - A 22-year-old Californian man who received oral sex from a sixteen-year-old girl should not be forced to register for life as a sex offender, the California Supreme Court ruled on Monday.

The state's top court found that California denied Vincent Hofsheier equal protection under the law because those having intercourse in such circumstances would not be forced to register as lifetime sex offenders.

Hofsheier appealed after being ordered to register his name on the list, which is shared with the public and carries significant stigma.

"Requiring mandatory lifetime registration of all persons who, like defendant here, were convicted of voluntary oral copulation with a minor of the age of 16 or 17, but not of someone convicted of voluntary sexual intercourse with a minor of the same age, violates the equal protection clauses of the federal and state Constitutions," the court ruled.

"We perceive no reason why the legislature would conclude that persons who are convicted of voluntary oral copulation with adolescents 16 to 17 years old...constitute a class of 'particularly incorrigible offenders'... who require lifetime surveillance as sex offenders."

U.S. law on oral sex has evolved over the years, and it was not until 1975 that oral sex between consenting adults was decriminalized in California. Today, in 38 of the 50 U.S. states consensual sex with a 16- or 17-year old is legal.

In the case, Hofsheier pleaded guilty and received probation after meeting the teenager in an Internet chat room and sharing rum and orange juice with her at a beach.

The California Supreme Court's decision returns the case to a lower court to decide whether he should still be subject to registration under that court's discretionary authority.