In order to get the ban on same-sex marriages reinstated, a group in California announced an emergency petition to the US Supreme Court.
On Friday, California's Ninth Circuit Court of Appeals in San Francisco lifted the ban on same-sex marriages, imposed under the so-called Prop 8 ballot measure, with immediate effect.
The first weddings were held within hours, notably for the two couples who challenged the ban, in high-profile ceremonies in San Fransisco and Los Angeles.
Just days earlier, the nation's top court had ruled supporters of Prop 8 lacked the proper standing to appeal a lower-court judgment that declared the measure unconstitutional.
The ruling essentially allowed the original federal court ruling to stand, striking down Prop 8.
But supporters of the ban, including ProtectMarriage.com, which backed legal efforts to uphold it, said the reinstatement of same-sex marriages was too hasty.
The Ninth Circuit court should have waited until at least 25 days after the Supreme Court ruling, ProtectMarriage.com said in a statement Saturday.
It argued that the appeals court had originally promised to wait until "final disposition" before lifting its injunction on same-sex marriages.
"Under Supreme Court procedural rules, 'final disposition' comes when the Supreme Court issues a 'mandate' to the Ninth Circuit, at least 25 days after announcing its opinion in the case.
"The 25-day waiting period is provided to allow parties such as Prop 8's proponents to petition the Supreme Court for a re-hearing of the case," the statement said.
"People on both sides of this debate should at least agree that the courts must follow their own rules," said ProtectMarriage.com coalition lawyer Andy Pugno in the statement.
"This kind of lawlessness just further weakens the public's confidence in the legitimacy of our legal system."
The group also called it suspicious that Friday's decision came "without any warning or notice to Proposition 8's official proponents".
Those challenging the ban, as well as LA mayor Antonio Villaraigosa and the California Attorney general, "all happened to be in position to perform same-sex marriages just minutes after", it added.
Supporters of Prop 8 have vowed to pursue their efforts to have the ban -- backed by 52 percent of Californians five years ago, with 48 percent against -- re-enforced.
But gay rights groups have cheered the Supreme Court ruling, as have many supporters of marriage equality.
"Thousands upon thousands of lives are about to change for the better, for good," said Human Rights Campaign president Chad Griffin in a statement Friday.
In the United States, 12 states, and the capital, allow same-sex couples to marry.