Pollies should decide on gay marriage: MP

Legalising same-sex marriage should not be left up to judges because they are divorced from mainstream society, Liberal MP Dennis Jensen says.

Dr Jensen, who has held the safe Liberal seat of Tangney since 2004, said it should be politicians who decide and while public sentiment was narrowly in favour of same-sex marriage, a referendum could make voters "swing the other way".

"You have to keep your finger on the pulse, if you don't you'll find yourself not being relevant to your community and you will get voted out," he told ABC radio.

The US Supreme Court ruled on Friday that marriage equality is a nationwide right and will now require all states to carry out and recognise same-sex marriage.

Dr Jensen said the ruling was judicial overreach and could pose unintended consequences like people petitioning the court to allow first cousin marriages, something which is already legal in Australia but banned in about half of the US states.

"In terms of equity and equality, what are the judges going to decide on that," he said.

Dr Jensen said he was personally opposed to same-sex marriage but had no problem with people loving and living with whoever they wanted or having the same legal rights as a married couple.

"I see marriage as fundamentally being about the bearing and rearing of children. It's about family."

Dr Jensen said he had not polled his constituents on same-sex marriage, but from the people he had spoken to he believed the majority were opposed to it.