Here are 10 developments in this big story:
The Centre had moved the top court today, seeking an immediate stay on Wednesday's High Court order which it called "erroneous", arguing that the verdict would adversely impact thousands of criminal cases pending across the country.
"There shall be a stay of operation of impugned judgement of Nov 6, 2013 passed by Gauhati High Court," said a bench of Chief Justice P Sathasivam and Justice Ranjana Desai at an urgent hearing held at the former's residence this afternoon.
The bench also observed that "the judgement has to be stayed as accused in two sensational cases have sought stay of the trial."
It was referring to former Telecom Minister A Raja and other accused in the 2G spectrum scam as well as Congress leader Sajjan Kumar, accused in the 1984 anti-Sikh riots case, who had cited the High Court's order to stop proceedings against them.
"We are concerned with all other CBI cases," the bench added after the Centre, in its appeal, had contended that the High Court's order directly impacted about 9,000 trials currently underway and about 1,000 investigations being undertaken by the CBI.
The Gauhati High Court had said that the CBI could not be treated as a police force; it could only conduct "inquiries". This meant the government's premier investigating agency stood to lose its power to probe, file FIRs or First Information Reports, arrest suspects and file charge-sheets.
The High Court order was based on the premise that the Union Home Ministry's order, under which the CBI was set up in 1963, was invalid as police investigations are under a state's purview. The court said the Centre had failed to prove that the CBI had been constituted as a special police force under the Delhi Special Police Establishment Act of 1946, from which it derives its powers to investigate. The Centre's resolution, it noted, was not even sent to the President and never received his assent.
But Attorney General Goolam E Vahanvati, appearing for the Centre today, said "the High Court's reasoning that the DSPE Act not applicable to CBI is a convoluted logic." The Centre had earlier contended that the CBI has stood the test of time.
The High Court's order had come on a petition challenging a CBI chargesheet on a Mahanagar Telephone Nigam employee.
The top court today issued notices to the petitioner as well as the Home Ministry and the CBI seeking their response on the High Court ruling.