In January, the Supreme Court granted a similar petition, halting marriages in Utah pending appeal of a federal ruling similar to Jones'.
The Supreme Court "made clear that it will decide the constitutionality of man-woman marriage, and until that time, no lower court decision holding against man-woman marriage should operate," Santai-Gaffney's petition says.
The plaintiffs in the Pennsylvania case, Whitewood v. Wolf, say Santai-Gaffney should not be allowed to intervene because Jones' ruling was "clear and unambiguous."
"This court declared the exclusion of same-sex couples from marriage unconstitutional and enjoined the defendants - including the secretary of health - from enforcing the law," the attorneys wrote.
Jeffrey Conrad, a lawyer working pro bono for Santai-Gaffney, said marriage was an issue for states to decide. In Pennsylvania, the petition argues, the people have decided that "a genderless marriage regime" is harmful to children and should not be legal.
Santai-Gaffney's petition relies on the same argument that her Montgomery County counterpart, D. Bruce Hanes, used last year in rejecting the ban - that as elected officials they took an oath to uphold the laws of the United States and the commonwealth.
Hanes last summer began issuing licenses to same-sex couples in spite of the ban, arguing that denying them would violate the constitution, and his oath of office.
A Commonwealth Court judge rejected Hanes' reasoning in November, calling the clerks' role "purely ministerial" with no authority to interpret laws.
Santai-Gaffney's attorneys also argue that because it did not involve a class-action lawsuit, Jones' ruling applies only to the plaintiffs named in the case.
Jill Engle, a law professor at Pennsylvania State University, called that argument ludicrous.
"When a federal judge opines that a statewide law must be 'discarded into the ash heap of history,' I don't think he is referring just to a few named plaintiffs," Engle said.
Jones, before his final ruling, wrote in a memorandum that "if this court renders a judgment in plaintiffs' favor, all clerks of the Orphans' Court would be subject to the legal mandate."
The day after Jones' ruling, when Corbett announced that he would not appeal, Conrad and other opponents of same-sex marriage began seeking a county official to step in.
He said Santai-Gaffney was the only one "who had the courage to step up." She could not be reached for comment Tuesday.
Despite her opposition to the practice - and her assertion that the ruling does not apply to her - Santai-Gaffney has been issuing marriage licenses to same-sex couples and will continue to do so until a court says otherwise, Conrad said.