Bundestag Vice President Johannes Singhammer of Angela Merkel's Bavarian sister party the CSU told Die Welt on Monday that his state's government should bring the matter of same-sex marriage to the Constitutional Court.
“In order to achieve legal clarity, I suggest that the Constitutional Court should be called upon,” Singhammer said.
He added that individual citizens could file a challenge anyway.
“It would be faster, however, if a state government were to do this - for example the Bavarian government,” Singhammer said. “I would advise this so that we can swiftly gain clarity on whether the new definition of marriage is unconstitutional.”
In a vote of 393 for to 226 votes against, the Bundestag (German parliament) passed a measure on Friday to allow same-sex marriage in Germany, which has long lagged behind its Western European neighbours in terms of LGBT rights.
While 75 conservative politicians were among those who voted for the change, Merkel and most of the members of the CDU/CSU parties voted against the measure, maintaining that they believed marriage should be between a man and a woman.
The vote changes the German legal code to state that “marriage is entered into for life by two people of different or the same sex", meaning same-sex couples will gain equal rights on adoption, as well as tax and inheritance.
The law has already been approved by the upper house and should come into effect by the end of the year.
But opponents argue that implementing the reform would require changing the Constitution, and therefore see the measure as potentially unconstitutional.
Justice Minister Heiko Maas also stated in 2015 that "the opening of marriage for same-sex couples would require a constitutional amendment," but he has more recently said that he believes amending the Constitution would be unnecessary.
Article Six of the Constitution regarding marriage does not explicitly mention gender in its definition, stating simply that “marriage and the family shall enjoy the special protection of the state”. But as Spiegel notes, the Constitutional Court has repeatedly interpreted the Constitution to mean that marriage only applies to heterosexual couples.
An amendment would also require a two-thirds majority vote, which proponents of same-sex marriage are unlikely to get unless there are drastic shifts in the Bundestag's party make-up come September's election.
The question of whether the state of Bavaria will actually file a challenge in court was still open on Monday, DPA reported. The state's Minister-President and CSU party leader Horst Seehofer would not give an answer on whether his government would pursue Singhammer's advice, but said that the matter must be legally and carefully examined.
“That will take some time,” Seehofer told DPA. “Therefore I cannot by any stretch of the imagination tell you whether the Free State of Bavaria will file a suit.
“I promote a mutual respect for marriage between a man and a woman, as well as for same-sex couples who take on such responsibility.”