Here are 10 developments in the story:
Nabam Tuki stands reinstated as chief minister of Arunachal Pradesh after the Supreme Court ruling, Attorney General Mukul Rohatgi told NDTV. "The Centre has nothing to do with this case. The Governor is party to this case. He will have to honour the Supreme Court judgment," he said.
The Attorney General's comments came after Prime Minister Narendra Modi's top ministers met this evening to review the court's order, seen as a setback for the ruling BJP, which had backed a government formed by Congress rebels.
Arunachal Pradesh was placed under President's Rule in January after the Nabam Tuki government was "voted out" in a controversial special session called by Governor JP Rajkhowa.
The governor had called the session in December, a month early, after 21 of 47 Congress lawmakers rebelled against Chief Minister Tuki.
The "special session" was held at a community centre and a hotel as the assembly building had been locked up on Speaker Nabam Rebia's orders. The Speaker later challenged in court the governor's right to call a session.
In February, the dissidents took power with the support of the BJP and independents, led by Kalikho Pul as Chief Minister.
"The government is run by numbers. The court doesn't run the government, numbers do. My government will remain," said a defiant Kalikho Pul, who plans to move a review petition.
In a damning indictment of the governor's actions, a five-judge Constitution bench of the Supreme Court said today: "The Governor must remain aloof from any disagreement, discord, disharmony, discontent or dissension, within individual political parties."
Many opposition parties crowed that the verdict has delivered another blow for the Modi government after the Supreme Court restored Uttarakhand to the Congress in May. "Thank you Supreme Court for explaining to the Prime Minister what democracy is," tweeted Congress Vice President Rahul Gandhi, whose party lost a key northeastern state, Assam, to the BJP in May.
BJP's Shrikant Sharma described the verdict as "vichitra" (odd) and said: "Rahul Gandhi is talking about democracy but he should know that past Congress governments have made a century of the use of Article 356 to dismiss state governments."
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