The Supreme Court upbraided the Centre for failing in its duty to protect Assam from 'external aggression' while striking down the Illegal Migrants (determination by tribunals) Act.

The Act, which put the onus of proving a person's nationality on the complainant, was struck down by the SC on Tuesday.

The Act was applicable only in the state of Assam. In other states, detection of foreigners is done under the Foreigners Act, 1946.

Also see: What is the Illegal Migrants Act

While striking down the IMDT Act as unconstitutional, a Bench comprising Chief Justice R C Lahoti, Justice G P Mathur and P K Balasubramanyan said it negated the mandate of Article 355 of the Constitution, which casts a duty on the Union government to protect every state against external aggression and internal disturbances.

The court took serious note of a report filed in 1998 by the then Assam governor Lt Gen S K Sinha about how the illegal migration was changing the demography in several districts of the state and encouraging insurgency in the region.

"This being the situation, there can be no manner of doubt that Assam is facing external aggression and internal disturbance on account of large-scale illegal migration of Bangladeshi nationals," Justice Mathur, writing the judgment, said.

Terming the IMDT Act as the 'main barrier' in identifying and deporting  illegal migrants, the court said the act came "to the advantage of such illegal migrants as any proceedings initiated against them under the said provision almost entirely ends in their favour, enables them to have a document having official sanctity to the effect that they are not illegal migrants."

The court said the presence of such a large number of illegal migrants from Bangladesh was in fact an aggression on the state of Assam and had also contributed significantly to causing serious 'internal disturbances' in the shape of insurgency.

"This made the life of the people of Assam wholly insecure and the panic generated thereby had created a fear psychosis. This resulted in hampering the growth of Assam although it had vast natural resources as people from the rest of the country had a general perception that it was a disturbed area curtailing investment and employment opportunities," it said.

"The impact is such that it not only affects Assam but it also affects its sister states like Arunachal Pradesh, Meghalaya, Nagaland etc., as the route to the said places passes through the state of Assam," Justice Mathur said.