Article 356 of the Constitution of India allows the President to take control of a state if the state government is unable to function constitutionally. This is known as President's Rule.
Article 356
Purpose
To restore stability and law and order in a state
When it applies
When the state government is unable to function constitutionally
How it's invoked
The President issues a proclamation based on a report from the state's Governor
Duration
Initially six months, extendable up to three years
Approval
Requires approval from both Houses of Parliament within two months
Extensions
Require a National Emergency or an Election Commission certification that elections cannot be held in the state
Judicial review
Subject to judicial review, meaning it can be challenged in court if deemed arbitrary
Article 356 is based on Section 93 of the Government of India Act, 1935. It's part of the Constitution's emergency provisions.
Article 356 empowers the Union government to assert its authority over a state if civil unrest occurs. It also allows Parliament to exercise legislative authority.