In an unprecedented move, the UN human rights chief has said she intends to intervene in India’s Supreme Court on the contentious Citizenship (Amendment) Act (CAA), prompting New Delhi to assert on Tuesday that no foreign party has such a right in matters related to the country’s sovereignty.

The UN high commissioner for human rights, Michelle Bachelet, informed India’s permanent mission in Geneva on Monday evening that her office would file an “intervention application” in the Supreme Court. People familiar with the development in Geneva said on Tuesday evening the brief was still being worked on and would be “filed shortly”.

The external affairs ministry opted to act pre-emptively, with spokesperson Raveesh Kumar saying the CAA was India’s internal matter and “concerns the sovereign right of the Indian Parliament to make laws”. He added, “We strongly believe that no foreign party has any locus standi on issues pertaining to India’s sovereignty.”

A draft of the application, accessed by HT, states that Bachelet wishes to assist the Supreme Court as “amicus curiae” (friend of the court) on the grounds that the challenge to CAA raises important issues related to international human rights law and its application to migrants, including refugees.

It states that her intervention is also based on “her mandate to inter alia protect and promote all human rights and to conduct necessary advocacy in that regard”. The application says she will tell the top court migrants within a country should receive equal and non-discriminatory treatment regardless of religion, legal status and documents they possess.

UN human rightsspokesman Rupert Colville confirmed Bachelet’s intention to submit an amicus curiae brief on the CAA in accordance with the Supreme Court’s established procedures, and that she had informed India’s permanent mission of her intention. “The amicus curiae {brief} will be filed shortly,” he said.

Colville said UN human rights chiefs have taken similar steps in the past in international, regional and higher national courts.

“The high commissioner has great respect for the Indian Supreme Court’s independence and importance, and in accordance with similar interventions in domestic jurisdictions by the high commissioner and her predecessors, the amicus curiae will focus on providing an overview of relevant and applicable international human rights standards and norms to support the court’s deliberations in the context of its review of the CAA,” he added.

External affairs ministry spokesperson Kumar, however, said India was clear the CAA “is constitutionally valid and complies with all requirements of our constitutional values”. The CAA is also “reflective of our long-standing national commitment in respect of human rights issues arising from the tragedy of the Partition of India”, he said.

Kumar added, “India is a democratic country governed by the rule of law. We all have utmost respect for and full trust in our independent judiciary. We are confident that our sound and legally sustainable position would be vindicated by the Supreme Court.”

Former external affairs minister K Natwar Singh described Bachelet’s move as “very unusual” and said it was unprecedented in India’s recent legal and diplomatic history. “This is a direct intervention by a UN agency and as far as my memory goes, I don’t recall any other such move,” he said.

Singh said the UN body’s intervention was unacceptable as India has a “good human rights record”. He added, “There were riots in Delhi but nobody is rejoicing. Everybody has condemned the violence.”

The CAA, passed by Parliament last December, seeks to fast-track the grant of citizenship to non-Muslim immigrants from Pakistan, Bangladesh and Afghanistan who arrived in India before December 31, 2014. The linking of citizenship with religion in the law triggered widespread protests in India, and Bangladesh Prime Minister Sheikh Hasina has questioned whether it was necessary.

Bachelet too has been critical of the CAA, telling a session of the UN Human Rights Council in Geneva on February 27 that the law “is of great concern”. She had said that Indians “in huge numbers, and from all communities, have expressed – in a mostly peaceful manner – their opposition to the Act, and support for the country’s long tradition of secularism”.

She also expressed concern at reports of “police inaction in the face of attacks against Muslims by other groups, as well as previous reports of excessive use of force by police against peaceful protesters”. Referring to the sectarian riots in Delhi, she had appealed to political leaders to prevent violence.

In December, the UN human rights office had described the CAA as “fundamentally discriminatory in nature”, as it appears to undermine the “commitment to equality before the law enshrined in India’s Constitution and India’s obligations under the International Covenant on Civil and Political Rights and the Convention for the Elimination of Racial Discrimination”.

The draft application further states that the Supreme Court’s examination of the CAA is of “substantial interest” to the UN high commissioner “considering its potential implications for the application and interpretation of India’s international human rights obligations, including the right to equality before the law and the prohibition of discrimination as well as the CAA’s impact on the protection of human rights of migrants”.

The application doesn’t expressly refer to the CAA violating international law and covenants, but instead states that Bachelet intends to provide the court with an overview of international human rights norms and standards related to the obligation of nations to protect persons at risk of persecution in their countries of origin.

It also states that any differentiation on the basis of religion by a law such as CAA should be objective and reasonable. The benefits of CAA, the application adds, are not afforded to people of any religion from countries other than Afghanistan, Bangladesh and Pakistan.

According to recent reports by UN human rights bodies, religious minorities, especially Ahmadi, Hazara and Shia Muslims in these three countries, warrant protection on the same basis as that provided in the preferential treatment proposed by CAA.

There have also been protests against a proposed all-India National Register of Citizens (NRC) and the potential problems that could arise from a combination of the CAA and NRC, aimed at identifying aliens living illegally in India. Protests against the CAA by largely Muslim groups and in favour of the law by Hindus erupted into violence in several neighbourhoods of northeast New Delhi last month, leading to the deaths of 47 people.