The second National Emergency was declared in December 1971, following the attack by Pakistan.
The third and final National Emergency was declared in 1975, due to internal disturbances. It lasted from June 25, 1975 to March 21, 1977.
The President of India can declare a National Emergency when they believe the country is threatened from internal or external sources, or from financial crisis.
During a National Emergency, the government can suspend civil liberties, cancel elections, and imprison political opponents.
The Right to Life and Personal Liberty cannot be suspended under the original Constitution. However, during the 1977 emergency, the government did suspend these rights.