Sir, though I fully agree with the views expressed by seniors and experts, particularly Sh. Dinesh Divekar ji & Umakanthan ji, I may submit for the kind consideration of seniors that in Central Govt. offices of the Govt. of India, principles of natural justice are strictly followed as far as taking departmental action is concerned. In Swami's Handbook 2007, the scope of a warning letter is mentioned as follows:
"Scope of a Warning Letter
(1) There may be occasions when a superior officer finds it necessary to criticize adversely a subordinate's work or call for an explanation, bringing the defects to notice and giving an opportunity to explain. If the lapse is not serious enough, like negligence, carelessness, lack of thoroughness, etc., to justify the imposition of the formal punishment of censure, but calls for some formal action such as the communication of a written warning/admonition/reprimand, it may be administered, and a copy of such a warning should be kept in the personal file of the subordinate.
(2) Written warnings, admonitions, or reprimands should not be administered or placed on record unless the authority is satisfied that there is good and sufficient reason to do so.
(5) A warning should not be issued as a result of regular disciplinary proceedings. If it is found that some blame attaches to the official, then the penalty of censure at least should be imposed.
(6) A warning is not a punishment." Swami's Handbook, as quoted above, is an authorized reference book on Central Govt. Employees Rules, etc.
Procedure for Disciplinary Action
Further, in one of the departmental manuals on disciplinary action procedures, the Central Govt. has advised its officers on the following procedure for taking disciplinary action against a delinquent employee:
(i) A Government employee violating the aforesaid provisions of the Conduct Rules for the first time should be advised by the appropriate disciplinary authority to desist from approaching Members of Parliament/Members of State Legislature to further his/her interest in respect of matters pertaining to his/her service conditions. A copy of this advice need not be placed in the CR dossier of the employee concerned.
(ii) If a Government employee is found guilty of violating the aforesaid provisions of the Conduct Rules a second time despite the issue of advice on the earlier occasion, a written warning should be issued to him/her by the appropriate disciplinary authority, and a copy thereof should be placed in his/her CR dossier.
(iii) If a Government employee is found guilty of violating the aforesaid provisions of the Conduct Rules, despite the issue of a warning, disciplinary action should be initiated against him/her by the appropriate disciplinary authority under the provision of CCS (CCA) Rules, 1965.
In view of the above, I feel that it will not be proper to conclude as "You can't issue a warning letter without conducting a domestic enquiry. It is a stigma on the worker's record, the courts have ruled. Issuing a warning letter without following the principle of natural justice is illegal," as mentioned by Mr. Shrikant_Pra. I hope Mr. Shrikant will refer to his post and guide us by providing a few citations of Hon'ble Court judgments (as requested also by Mr. Divekar) in support of his comments so that we may update ourselves accordingly.