UPDATE 3-Businesses back gay marriage, top U.S. court sets argument date
(Adds business brief has been filed, paragraph 2, and adds details of conservative brief, paragraphs 3-4)
By Lawrence Hurley
WASHINGTON, March 5 (Reuters) - Big business rallied behind the gay marriage cause on Thursday as the U.S. Supreme Court scheduled oral arguments for April 28 on the contentious social issue that promises to yield one of the justices' most important rulings of 2015.
A total of 379 businesses and groups representing employers across various sectors, including Google Inc, American Airlines Group Inc, Goldman Sachs Group Inc and Johnson & Johnson, have signed on to a friend-of-the-court brief in support of gay marriage that was filed on Thursday.
Various supporters of gay marriage are filing similar briefs ahead of a Friday deadline. One was filed on behalf of dozens of prominent conservatives, including former Republican National Committee Chairman Ken Mehlman and David Koch, one of the billionaire Koch brothers known for donating to right-leaning political causes.
The brief says that "conservative values are consistent with - indeed, are advanced by - affording civil marriage rights to same-sex couples."
The administration of President Barack Obama is also due to file a brief backing gay marriage.
The court must decide whether states have the right to ban gay marriage. The nine justices will hear an extended 2-1/2-hour argument in cases concerning same-sex marriage bans in Ohio, Michigan, Kentucky and Tennessee.
The justices will consider whether same-sex marriage bans are prohibited by the U.S. Constitution's guarantee of equal protection under the law. A ruling is due by the end of June. Continued...