Why are India's top judges doubting each others' sanity?

The Indian judiciary is in the midst of an unprecedented crisis which has resulted in rival judges issuing court orders for each other to undergo mental health evaluations. The BBC's Geeta Pandey unravels an extraordinary series of events.

For the past several months now, Justice Chinnaswamy Swaminathan Karnan of the Calcutta High Court has been on a massive collision course with the top judges of India's Supreme Court.

On Monday, matters came to a head when a seven-judge Supreme Court bench, that included India's Chief Justice JS Khehar, ordered a psychiatric evaluation of Justice Karnan by a panel of government doctors to ascertain if he was mentally ill.

An angry Justice Karnan responded by ordering similar tests on the seven top court judges.

The present standoff began on 23 January when Justice Karnan wrote a letter to Prime Minister Narendra Modi with the names of 20 "corrupt judges" and three senior law officials.

Even though he failed to provide any evidence against those named in the list, he urged Mr Modi to investigate - and take action against them.

On 8 February, the seven-judge bench decided that this - and other similar letters Justice Karnan had sent in the past accusing his fellow judges of corruption and bias - was "contempt of court" and demanded an explanation from him.

On 13 February, the day he was due to appear in court, Justice Karnan did not show up. The top court gave him another chance and asked him to come on 10 March.

But when he ignored that date too, the Supreme Court issued a "bailable warrant" against him, ordering the West Bengal state police chief to bring him in on 31 March.

He was also barred from performing any judicial or administrative functions until further orders.

But the rebel judge did not fall in line.

On the same day, he too passed an order - a low-caste Dalit (formerly untouchable), he accused the seven judges of caste bias and ordered that a case be registered against them for discriminating against him.

He also "ordered" them to pay him 140m rupees ($2.2m; £1.7m) in compensation.

A few days later, when the arrest warrant was served to him, he "rejected" it saying it was "illegal" and "unconstitutional".

And it's gone rapidly downhill since then.

Last Friday, Justice Karnan stunned India when he passed an order banning the chief justice and the other six judges from leaving the country.

From a makeshift court he's set up at his home since being barred from the high court, he directed the Air Control Authority in Delhi to prevent the judges from travelling abroad while they were being tried for caste bias against him.

He also ordered the judges to appear at his "home-court" on 1 May - the same day they had asked him to appear in the Supreme Court.

On that day, the Supreme Court judges asked whether Justice Karnan was "feigning mental imbalance" and ordered a panel of doctors to examine him on 4 May.

The director general of police (DGP) in West Bengal was ordered to provide a team of officers to help the medical board carry out the examination and the board was ordered to submit its report by 8 May.

The judges believed they were being considerate - they said from what Justice Karnan had been saying at his news conferences and from the "orders" he had passed in recent days, it seemed he might not be able to defend himself in court.

But that did not please the rebel judge.

He said that he was "of sound health and mind", that his wife and two sons are "very much satisfied" with his physical and mental health, that the court order was "an insult to a Dalit judge", and that he would not undergo a medical test.

Within hours, he had also passed his own "counter-order" - directing the director general of police (DGP) in Delhi to send the seven judges before a psychiatric board to check if they were mentally ill and bring the report to him by 7 May.

Now Delhi police is headed by a commissioner and there's no DGP, but that is a minor quibble considering the battle involves India's top judges.

A rebel without a pause.

During his seven-year tenure as a high court judge in Chennai (Madras) from 2009, he accused at least two chief justices of discriminating against him because of his caste.

He also accused a fellow judge of raping an intern - a claim yet to be proven.

On a few occasions, media reports said he also barged into other judges' courtrooms and generally antagonised his colleagues, so much so that at the end of 2014 several of his fellow judges petitioned the chief justice of India, demanding his transfer because they couldn't work with him.

A year ago, when the Supreme Court did transfer him to Kolkata (Calcutta), he passed an order staying his own transfer.

It was only after a closed-door meeting with the then chief justice of India, TS Thakur, that he agreed to move.

No-one really knows - it's the first time ever in India that the top court has invoked contempt proceedings against a sitting high court judge.

The next important date on the calendar is 4 May - the day Justice Karnan is due to undergo psychiatric evaluation. But it's unlikely that he could be forced to see the doctors against his will.

Legal experts say they expect the case to drag on at least until 12 June - the day he turns 62 and retires.

The Supreme Court may be in a better position to take action against him once he's hung up his robes.