To protect the family as an institution in the United States, the chief justice of the state of Alabama vowed to push for a constitutional ban to same-sex marriages, which have been legalised across the country by the Supreme Court.

Alabama Supreme Court Chief Justice Roy Moore, also known as "Ten Commandments Judge" for his conservative stance, launched an online petition in the past days to amend the US Constitution and limit marriages only to a union between man and woman.

Moore is proposing the introduction of this provision to the US Constitution: "Nothing in this Constitution or in the constitution or laws of any state shall define or shall be construed to define marriage except as the union of one man and one woman, and no other union shall be recognised with the legal incidents thereof within the United States or any place subject to their jurisdiction."

This move is in response to the Supreme Court's ruling this week to legalise same-sex marriages in the US, with five justices saying it is a fundamental right guaranteed by the Constitution.

Moore, however, opined that the US Constitution does not say anything about gay marriage.

"Five judges on the Supreme Court, or justices, have presumed to find a fundamental right which has no basis in the history or logic or tradition of our country," the Alabama Supreme Court justice said in an interview with CNN.

He also said that the recent high court decision on same-sex marriage actually "contradicts" the Constitution.

"It's a travesty. The courts are exercising wrongful authority over this country," Moore said.

"If marriage falls, the institution of family upon which it is based falls," he added.

Moore noted that the Supreme Court can still be asked to reconsider its decision on same-sex unions within 25 days of a ruling.