The government had made an exception for PJ Thomas, the central vigilance commissioner (CVC) in the middle of the controversy over his appointment, to enable him to come to Delhi on his first stint at the Centre in 2009.
As rules existed then, Thomas was not eligible for a post at the Centre, but the government amended them to suit the CVC.
The government creates a shortlist of officers who can hold the posts of joint secretary and above at the Centre. If an officer doesn't make it to this panel, he can't serve in Delhi, irrespective of seniority back home.
One of the conditions of getting into this panel is that the officer should have served in the central government for at least three years.
The rule came into force in 2006 on the ground that officers who did not have the previous experience of working for the Centre would not be able to deliver.
But Thomas was empanelled to hold a secretary's post in 2007 though he had never served in Delhi.
"The rules were amended to enable officers - who could not be empanelled earlier due to pending vigilance cases, which were later found to be without any basis - to be empanelled as secretary," an official familiar with personnel policies of the government told HT.
"This exemption covered Thomas."
The official suggested Thomas may have been the only officer to benefit from this change.
"In the government, it is easier to change rules than make exceptions for people," he said.
This exemption enabled Thomas to join the Centre, first as parliamentary affairs secretary from January to October 2009 and then as telecom secretary.
The same condition was, however, used to prevent the empanelment of other officers, including Bijay Patnaik, who is Orissa's chief secretary.
"Patnaik complained that it was an unfair rule but no one relaxed it for him," the official said.