The former Liberal minister Philip Ruddock has been appointed to examine if Australian law adequately protects the human right to religious freedom.

Ruddock’s appointment by cabinet, announced on Wednesday, is designed to head off a bruising debate about religious amendments in a same-sex marriage bill, but the treasurer, Scott Morrison, said the review was “no substitute” for those amendments.

The prime minister, Malcolm Turnbull, said it was important to look at the issue of religious freedom carefully, in light of the yes vote and impending legislation on marriage equality.

While senior conservatives including Peter Dutton and Mathias Cormann have publicly suggested a religious freedom bill can be considered next year, separately to a marriage bill, others including Morrison and Liberal senator, David Fawcett, have insisted it be considered at the same time. Ruddock has been asked to report by 31 March.