The Supreme Court, in its detailed analysis of the Sarbananda Sonowal v. Union of India case, reaffirmed that large-scale illegal immigration constitutes "external aggression" under Article 355 of the Constitution. This article mandates the Union to protect states against such threats.

The Court held that the influx of immigrants from Bangladesh into Assam post-1971 posed a severe security threat to the state, thereby violating Article 355.

The judgment authored by Justice Surya Kant, also on behalf of Justice MM Sundresh and Justice Manoj Misra emphasized that illegal immigration amounts to "external aggression" under Article 355, a broader term than "war," as it involves complex situations that can destabilize national security without direct conflict between nations.

The case centered on a challenge to the constitutional validity of the Illegal Migrants (Determination by Tribunals) Act, 1983 (IMDT Act), which was specific to Assam. The petitioner, Sarbananda Sonowal, argued that the IMDT Act was ineffective in identifying and deporting illegal immigrants, in contrast to the Foreigners Act, 1946, which was applicable to the rest of India.

The Court, agreeing with the petitioner, observed that the IMDT Act set a higher threshold for establishing someone's status as an illegal immigrant and thereby provided undue shelter to immigrants who entered Assam after 1971. The Court deemed the Act unconstitutional, as it compromised the state’s security and violated Article 355.

"We respectfully agree with Sarbananda Sonowal (supra) in its holding that the term aggression in Article 355 is of a wide import and can include unabated migration if it poses a threat to the security of the state. Therefore, in such cases, the Union indeed bears a duty to protect the State from such unabated immigration that it amounts to external aggression or internal disturbance; and those statutes which violate this duty can be held unconstitutional," the Court said

However, when discussing the applicability of this doctrine to Section 6A of the Citizenship Act, which grants citizenship to certain groups of immigrants from East Pakistan (Bangladesh), the Court made a distinction.

Section 6A was introduced as part of the Assam Accord to address the issue of immigration into Assam from 1966 to 1971. Unlike the IMDT Act, Section 6A does not encourage uncontrolled migration but instead establishes clear criteria for obtaining citizenship. The Court ruled that this section does not amount to "external aggression" as it regulates immigration within a specific timeframe and ensures the detection of illegal immigrants post-1971.

The Bench noted, "In the present case, Section 6A is limited in its ambit and does not by itself create unabated migration or legitimize its continuance.... Section 6A segregates immigrants from East Pakistan to Assam into three classes. It grants deemed citizenship only to the immigrants who migrated before 01.01.1966, and citizenship by registration to immigrants between 01.01.1966 and 25.03.1971. Further, when read along with other legislations on immigration and citizenship, it declares by implication, immigration into the State post-1971, as illegal. In fact, Section 6A adopts a practical solution for the problem of incessant illegal immigration into Assam by devising an implementable solution keeping in mind India’s commitments, international relations and administrative realities."

"Not only this, as was deliberated in the section on ‘manifest arbitrariness’, the migrants also need to satisfy certain conditions for invoking Section 6A, apart from being persons of Indian origin and ordinary residents in India. Hence, unlike the immigration scrutinized in Sarbananda Sonowal (supra), Section 6A addresses a controlled and regulated form of immigration that in our opinion would fall short of ‘external aggression’," the Court said.

The Court held, "Hence, the claim of the Petitioners regarding Section 6A being contrary to Article 355 cannot be accepted. However, that being said, upholding the constitutionality of Section 6A should not be construed as an impediment in implementing existing citizenship and immigration legislations, or giving effect to other judicial decisions controlling the field."

Cause Title: In Re Section 6A of the Citizenship Act 1955 [Neutral Citation No. 2024 INSC 789]