In a submission to the Legal and Constitutional Affairs Committee of Australia's Senate, Amnesty's Australian affiliate contends that laws limiting the right to marry to opposite-sex couples amounts to "arbitrary discrimination" in contravention of the International Covenant on Civil and Political Rights (ICCPR).

The group further interprets a provision of the ICCPR guaranteeing adults the right to enter into ["consensual marriage" as applying to same-sex couplings. Critics contend this distorts the meaning of the word "marriage" without regard to context and the apparent intent of the drafters. The ICCPR provision cited, Article 23, states that "The right of men and women of marriageable age to marry and to found a family shall be recognized," and that "No marriage shall be entered into without the free and full consent of the intending spouses."

Underscoring what critics say is the problem of United Nations (UN) treaty monitoring bodies exceeding their mandates and seeking to reinterpret treaties to include novel concepts not agreed upon by those who negotiated or ratified the treaties, Amnesty asserts that "For more than a decade, non-discrimination on the grounds of sexual orientation has been an internationally recognized principle which has been endorsed by UN treaty bodies and numerous inter-governmental human rights bodies." Specifically, Amnesty cites interpretations of the ICCPR and the International Covenant on Economic, Social and Cultural Rights by their respective treaty monitoring bodies as forming a soft-law jurisprudence in favor of a new non-discrimination category.

The creation of such a non-discrimination category is hotly-contested among UN member states, however. To date, efforts to enshrine "sexual-orientation and gender identity" as a category on par with ones such as race and religion in a legally binding document have been repeatedly rejected.

Amnesty points to a French-initiated statement signed by roughly 65 member states, including Australia, last December asserting the existence of a non-discrimination category based on sexual orientation and gender identity in support of Amnesty's call to allow same-sex couples to enter into "a legally binding union of couples, otherwise known as marriage." The Amnesty submission contends that preventing "same-sex couples from entering into a legally binding union on the basis of sexual orientation" contravenes "the statement Australia supported in the UN General Assembly last year."

A contemporaneous counterstatement, however, signed by nearly 60 nations, principally from the Islamic world, Africa and Oceania, along with independent statements made by Russia, Belarus and the Holy See, pointed out that no non-discrimination category based on sexual orientation and gender identity exists in international law. Amnesty's submission makes no reference to the counterstatement.

Critics of the French-led statement pointed out at the time that, though non-binding and supported by only a minority of member states, advocates would hail it as a soft-law norm signaling of a movement by states toward a rights-based acceptance of homosexual conduct - in this particular case, using it to place same-sex unions on par with marriage.