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"We've decided to insert this into the Marriage Act to make it very plain that that is our view of a marriage and to also make it very plain that the definition of a marriage, that should rest in the hands ultimately of the parliament of the nation," he said.

"[It] should not over time potentially be subject to redefinition or change by courts. It is something that ought to be expressed through the elected representatives of the country and that is what we have decided to do."

Howard continues to oppose a plebiscite, telling 2GB radio in March the matter ought to be resolved in parliament.