The letter from UN Assistant Secretary General for Legal Affairs Stephen Mathias was submitted in a US court by Khobragade's lawyer Daniel Arshack to bolster the claim that she had immunity when she was arrested in December for allegedly making false declarations in a visa application for her maid.
Arshack said the 39-year-old diplomat was credentialed as a "Special Advisor" to the UN from August 26 to December 31 last year.
He said Khobragade was appointed an advisor in August last year ahead of Prime Minister Manmohan Singh's visit for the UN General Assembly session.
Given that Khobragade had a UN credential of Special Advisor, she was immune from arrest on December 12 and prosecution on visa fraud charges, he said.
Arshack submitted the letter from the UN Assistant Secretary General as an exhibit in court along with his motion to dismiss the indictment against Khobragade.
The letter states that according to the Convention on the Privileges and Immunities of the UN adopted by the General Assembly, "...representatives of members to the principal and subsidiary organs of the United Nations and to conferences convened by the United Nations shall, while exercising their functions and during their journey to and from the place of meeting, enjoy the...privileges and immunities" set forth under sections of the Convention unless the person is a "representative in a state of which s/he is a national or of which s/he has been a representative".
It said the expression representatives "shall be deemed to include all delegates, deputy delegates, advisers, technical experts and secretaries of delegations".
The letter clarified that application of the rules of immunities in any specific situation "would depend on the facts and circumstances of the specific situation".
Khobragade was strip-searched and held with criminals after her arrest, triggering a diplomatic row between India and the US. After her indictment on visa fraud, she returned to India in January after she was asked to leave the US by the State Department.
Assistant Secretary-General Mathias said in the letter that the UN office of legal affairs provides formal opinions only at the request of inter-governmental bodies of the UN or at the request of UN departments and offices.
He said he was responding on an "informal basis" to India's questions about privileges and immunities enjoyed by UN officials.
"We are responding to your questions on an informal basis and would appreciate your conveying this to your government," Mathias said in the letter addressed to India's Deputy Permanent Representative to the UN Bhagwant Bishnoi.
He further said the legal affairs office does not provide formal legal opinion to UN member states, including those concerning the interpretation and implementation of the Convention.
Arshack said Khobragade had immunity when she was appointed Deputy Consul General at the Indian Consulate in New York and following her transfer to India's Permanent Mission to the UN.
He also submitted in court a computer screen shot of the UN Protocol and Liaison Service's listing of Khobragade's accreditation as an advisor to the UN for the General Assembly meeting.
In previous motions, Arshack told the court Khobragade had full diplomatic immunity at the time of her arrest since she was appointed a Special Advisor to the UN in August last year.
"Obviously, the (US) Government knew when it obtained that indictment that there could be no prosecution of Khobragade since her diplomatic status had already been changed and she was therefore immune from prosecution," Arshack said.
It was due to her diplomatic status that Khobragade did not get arraigned on the indictment, he said.
Arshack said Khobragade's immunity "should have prevented" her arrest, handcuffing, jailing, strip-searching and imposition of bail conditions.
"This proceeding has been wrongfully commenced against Khobragade. She should not have been arrested in the first place and she was indicted despite the fact that the government knew that her diplomatic status precluded a prosecution of Khobragade," he said.
The Manhattan federal prosecutor, Indian-origin Preet Bharara, had filed a memorandum in federal court opposing Khobragade's motion to dismiss her indictment.
He also submitted a US Department of State declaration that concludes Khobragade did not enjoy immunity from arrest or detention at the time of her arrest and that she does not enjoy immunity from prosecution for the crimes in the indictment.
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