The main legal point established in the judgment is that an unequivocal promise or representation is necessary for the application of principles of estoppel and promissory estoppel. In the absence of such a promise or representation, the court cannot enforce the equity in question against statutory prescriptions.

1. The petitioner was an Assistant Executive Engineer of the Cochin Shipyard Ltd., a company registered under the Companies Act. Under schemes of technical exchange, the Government of India was sponsoring candidates for employment in foreign countries. On 19-11-1977 the Central Government wrote Ext. P1 letter to the company about possibilities of utilising the services of its engineers in assignments abroad, suggesting that interested personnel register their names for inclusion in appropriate panels. The petitioner applied for registration, and his application was forwarded by the company. He was selected for employment under the Government of Iraq in its Ministry of Agriculture and Agrarian Reforms. On 17-7-1980 the Central Government advised the company as per Ext. P3 letter to release the petitioner, grant him a no-objection certificate, and treat him "as on deputation to a foreign government in the public interest, with lien retained in the post held by him". But on 19-7-1980 another employee of the company similarly selected for service abroad was informed that he would have to resign from the company's services, if he was to take up the foreign assignment Apprehending that similar conditions involving loss of lien would be imposed on the petitioner also, he filed the present Original Petition on 28-7-1980; and on 29-7-1980 this Court gave an interim direction that he be relieved from duty, leaving the question of retention of lien to be decided in the writ petition. The petitioner was accordingly relieved, but it appears that an order (Ext. R3) was issued by the company on the same day informing him that he too would have to resign, for taking up the foreign assignment; The petitioner has served his term in Iraq and is now said to be back in India.

2. The main prayer in the writ petition as it now stands after due amendment, is to quash Ext. R3. According to the petitioner, the company had represented to him that he could take up assignments abroad on condition that his lien would be retained during the period of foreign service. Acting on this representation, he entered into a contract of service with the Iraq Government, thereby altering his position. The company is estopped under the circumstances from insisting that he should resign and surrender the lien. The company is a public sector undertaking and a 'State' as defined in Art.12 of the Constitution. The scheme for foreign service was itself sponsored by the Central Government, for lending the services of Indian experts to foreign governments on short-term basis, with provision for retention of lien. The company had accepted this scheme and encouraged the petitioner to participate in its working; it could not go back on the assurance and leave him high and dry, against the settled principles of promissory estoppel.

3. Broadly stated, estoppel is a rule which estops or prevents a person, by reason of certain circumstances, from urging a plea or proving something which he could otherwise do, in a Court of Jaw. It is primarily a rule of evidence. Estoppels are generally classified into three: (1) estoppel by record (2) estoppel by deed, and (3) estoppel in pais.

4. Estoppel by matter of record is mainly concerned with the effect of judgments and their admissibility in evidence. For instance, S.40 of the Evidence Act provides that the existence of a judgment which prevents a court from taking cognizance of any suit is relevant, when the question is whether the court ought to take cognizance of it. A binding decision inter parties operating as res judicata can thus be pressed into service by a defendant to estop the plaintiff from enforcing a claim. Res judicata is in a sense estoppel by judgment, though it is really a prohibition against the court from enquiring into a matter, while estoppel in the strict sense is a prohibition against a party.

5. Estoppel by deed prevents a person from averring or proving anything contrary to what he has solemnly averred in