JUDGMENT : ( 1. ) B. M. LAL J. :- The Order passed in this Petition shall also govern the disposal of the Miscellaneous Petitions Nos. 966 of 85 (Miss Sarita v. State and others), No. 967/85 (Deo Karan v. State and Others), No. 969/85 (Miss Rahman v. State of M. P. and others), No. 971/85 (Shyam Singh v. State of M. P. and others,) No. 972/85 (Prakash Chandra V. State of M. P. and others), No. 973/85 Rameshwar v. State of M. P. and others), No. 974/85 (Shankar Singh v. State of M. P. and others), No. 968/85 (Smt. Mangla v. State of M. P. and Others), No. 970/85 (Badrilal V. State of M. P. and others), No. 976/85 (Govind v. State of M. P. and others), No. 977/85 (Smt. Triveni v. State of M. P. ,and others), No. 978/85 (Brijraj v. State of M. P. and others), No. 979/85 (Ganpat Singh V. State of M. P. and others), No. 980/85 (Asfaan Mohd. Khan v. State of m. P. and others), No. 1084/85 (Miss Sangita v. State of M. P.), No. 1085/85 (Jeewan prasad v. State of M. P. and others), No. 1086/85 (Dilawar Khan v. State of M. P. and others), No. 1087/85 (Vikral Singh v. State of M. P. and others), No. 1088/85 (Jagdish chandra v. State of M. P. and others), No. 1089/85 (Mahipal Singh v. State of M. P. and others), No. 1090/85 (Dashrathlal v. State of M. P. and others), No. 1091/85 (Jagdish chandra v. State of M. P. and others), No. 1092/85 (Smt. Rajkumari v. State of M. P. and others), No. 1094/85 (Smt. Manorma v. State of M. P. and others), No. 1095/85 (Ranchhor v. State of M. P. and others), No. 1097/85 (Mansukhlal v. State of M. P. and , others), No. 1098/85 (Pratap Singh v. State of M. P. and others), No. 1099/85 (Indrajeet singh v. State of M. P. and others), No. 1100/85 (Girdharilal v. State of M. P. and others), No. 1101/85 (Randhashyam No. 1101/85 (Randhashyam v. State of M. P. and others), No. 1103/85 (Madanlalv. State of M. P. and others), No. 1104/85 (Smt. Ratna devi v. State of M. P. and others), No. 1105/85 (Smt. Rekha v. State of M. P. and others), No. 1106/85 (Surendra Chandera v. State of M. P. and others), No. 1107/85 (Rasool Khan v. State of MP. State of M. P. and others), No. 1104/85 (Smt. Ratna devi v. State of M. P. and others), No. 1105/85 (Smt. Rekha v. State of M. P. and others), No. 1106/85 (Surendra Chandera v. State of M. P. and others), No. 1107/85 (Rasool Khan v. State of MP. and others), No. 1109/85 (Miss Asha v. State of M. P. and others), No. 1110/85 (Ramlal v. State of M. P. and others), No. 1111/85 (Nand Singh v. State of M. P. and others), No. 1112/85. (Heeralal v. State of M. P. and others), No. 1113/85 (Bhikram Singh v. State of M. P. and others), No. 1114/85 (Lokendra Kumar v. State of M. P. and others), and No. 1093/85 (Ramsingh v. State of M. P. and others ). ( 2. ) BY this bunch of petitioners, the petitioners who are teachers are seeking a writ of certiorari, quashing the modified orders passed by the various District education Officers of the State, deeming the petitioners appointment as ad hoc for a limited period upto 30-4-1985. The petitioners further seek a writ of mandamus directing the respondents to continue them in service after 30-4-85 and that their terms of appointment be treated as regular instead of ad hoc. ( 3. ) IN nutshell, the facts leading to the present bunch of petitions, are as under : on 5-10-84 the Education Department, Government of Madhya Pradesh took a decision to fill up 400 posts of teachers and 800 posts of Assistant Teachers. In consequence of that decision, the respondents invited applications through employment Exchanges of various Districts. The concerned Employment Officers intimated the petitioners, whose names were registered in the Employment Exchange offices, that their names had been sent for appointment as teachers/assistant teachers and also intimated that in "case of their appointment, at the first instance, they will get fixed salary of Rs. 300/- per month for a period of two years and then scale of pay Rs. 545-925 will be given. This was on the basis of the intimation received by the employment Officers from the concerned State Government authorities. ( 4. ) ACCORDINGLY, the petitioners appeared before the respective District selection Committees which took interview and then they were appointed as teachers/assistant teachers on the same terms and conditions as stated in the interview memo issued by the Employment Officers. ( 5. ( 4. ) ACCORDINGLY, the petitioners appeared before the respective District selection Committees which took interview and then they were appointed as teachers/assistant teachers on the same terms and conditions as stated in the interview memo issued by the Employment Officers. ( 5. ) SUBSEQUENTLY, on 10-2-1985, the State Government revised their earlier decision and as such the terms and conditions of earlier appointment of the petitioners were changed from regular to ad hoc limiting the tenure of the appointments upto 30-4-85. Accordingly, all the respective District Education Officers issued orders and intimated all the concerned assistant teachers, i. e. the petitioners. ( 6. ) THIS change of service conditions gave rise to this bunch of petitions by which the present petitioners are invoking writ jurisdiction of this Court under articles 226 and 227 of the Constitution of India. ( 7. ) IN these petitions the petitioners have been represented through their respective counsel, but their main submission is common, as the points in issue involved in all the petitions are the same, i. e.- (i) Once the terms of employment are settled and communicated, they form part of the service contract and cannot be changed behind the back of the petitioners, (ii) Once the respondents have given in writing as to the terms and conditions of service and acted upon, they are bound by the principle of promissory Estoppel and as such the service conditions cannot be changed, and - (iii) The said orders also suffer from the doctrine of equality as envisaged under Articles 14 and 16 of the Constitution of India, resulting in hostile discrimination against the petitioners. ( 8. ) DENYING the averments of the petitions, the respondents emerged with a plea that the grounds as have been taken in the petitions and raised before the Court, have no legal force and therefore, the order passed by the State Government being valid in all respects, the petitions deserve to be dismissed. ( 9. ) AFTER hearing the arguments at length and giving our anxious thoughts to the points in issue, we have reached the conclusion that these petitions have no merit and deserve to be dismissed. ( 10. ( 9. ) AFTER hearing the arguments at length and giving our anxious thoughts to the points in issue, we have reached the conclusion that these petitions have no merit and deserve to be dismissed. ( 10. ) IT is not disputed that the Madhya Pradesh Non-Gazetted Class III educational Service (Non-Collegiate) Recruitment and Promotion Rules, 1973 (hereinafter referred to as the rules) framed under Article 309 of the Constitution of india, came into force in the year 1973. Rule 10 of the Rules provides the mode of selection of the Teachers/assistant Teachers by conducting examinations and thereafter taking interview by the statutory committee, constituted under the said rules, whereas without conducting any examinations, according to the respondents, the following selection committee was constituted consisting of-Collector as Chairman district Education Officers as Secretary district Employment Officer as Member and district Organiser, Tribal Welfare Department as Member, for each district which was not according to Rule 10 (1) read with Schedule 4 of the rules and therefore the said Committee which took interview of the petitioner was not a statutory committee. ( 11. ) NOW, this being the legal position, if the appointments of the petitioners are tested with the touchstone of the provisions of the statutory Rules to know as to whether their appointments have been made in conformity with Rule 10 of the Rules, then it will be seen that the petitioners appointments spell out that the same have not been made in conformity with the Rules. ( 12. ) THE appointment orders in the present set of petitions do disclose that the appointment of the petitioners have not been made in accordance with Rule 10 of the rules as no selection committee was constituted in accordance with Schedule IV of the Rules, but the selection and recommendation were made by the committee which was not constituted in accordance with the Rules, therefore, the petitioners appointment having not been made in conformity with the Rules, cannot be saved. ( 13. ( 13. ) IT is further seen that the memorandum for constitution of the selection committee in the instant case was not more than a memo issued by the State government inits executive capacity whereas the Rules referred to above have been framed under Article 309 of the Constitution of India and therefore, the memo which is nothing more than an executive direction of the State Government, cannot be acted upon in contravention of statutory Rule 19 (3) read with Schedule-4 of the Rules. (See i. N. Saksena v. State of M. P. , A. I. R. 1967s. C. 1264 and B. N. Segarajan and others v. State of Kamataka and others, A. I. R. 1979 S. C. 1676. ). Thus, the legal position which emerges is that the executive instructions cannot be acted upon contrary to the statutory provisions nor can such instructions, if any, over-ride the statutory provisions of law. This being the legal position, the orders by which the petitioners had been appointed demonstrate that they have been appointed in utter disregard to the statutory provisions of Rule 10 (3) of the Rules and therefore, the question of settling terms of employment does not arise and as such the said term of employment which is contrary to the provision of law, will not form part of service contract and could be changed as soon as it is known or brought to the notice of the authority concerned. ( 14. ) THE next submission made by the learned Counsel for the petitioners, was about promissory estoppel. The doctrine of promissory estoppel, as pleaded by the learned counsel is that once the petitioners having been appointed by the orders of the district Education Officers, the same cannot be modified to the detriment of the petitioners revising the condition of service from regular to ad hoc and that too upto a limited period i. e. upto 30-4-1985 and as such the State is estopped to treat the petitioners appointment as ad hoc. In our opinion, this contention has no substance and must be repelled. ( 15. ) AS pointed out earlier, the appointments of the petitioners have been made against the statutory provisions of law by violating the statutory Rules. In our opinion, this contention has no substance and must be repelled. ( 15. ) AS pointed out earlier, the appointments of the petitioners have been made against the statutory provisions of law by violating the statutory Rules. Therefore, there does not arise any question of application of doctrine of promissory estoppel against the orders issued by the District Education Officers, which are patently ex facie illegal being contrary to the statutory Rules. It is settled law that there can be no estoppel against the statute. Further, the doctrine of promissory estoppel will apply against an order which is a valid order in all respects but not against an order which is invalid, as is apparent in the instant case. (See Union of India and others v. Godfray phillips India Ltd. (1985) 4 Supreme Court Cases 369. Therefore, question of application of doctrine of promissory estoppel does not arise. ( 16. ) IT is then argued that changing of the service conditions of the petitioners violates Articles 14 and 16 of the Constitution of India. In our opinion, where the appointment order is found to be illegal being against the statutory provisions, in such cases Article 14 or 16 cannot be invoked. Further, it has not been pointed out by the learned counsel for the petitioners that some teachers have been retained despite their orders being invalid. Therefore, no question of discrimination arises. ( 17. ) IT further suffices to say that on discovery of some mistake, irregularity or incompetency in passing the appointment order which is inherently invalid, on rectifying the same, even if services are terminated, that cannot be construed to be an act of discrimination. Similarly, in the instant case, while rectifying the earlier order, which is admittedly, passed against the statutory rules, if term and service conditions of the petitioners appointments were unilaterally changed, such a rectification cannot be said to be violative of Article 311 or even Article 14 or 16 of the Constitution. In abdul Hafiz Khan v. Govt. of M. P. , 1964 M. P. L. J. 447 a Division Bench of this Court held that if an appointment is found invalid on discovery of mistake and is in consequence thereof even if termination order is passed, that will not be against article 311 of the Constitution. In abdul Hafiz Khan v. Govt. of M. P. , 1964 M. P. L. J. 447 a Division Bench of this Court held that if an appointment is found invalid on discovery of mistake and is in consequence thereof even if termination order is passed, that will not be against article 311 of the Constitution. Therefore, in the instant case modifying the earlier order and making it ad hoc upto 30-4-85 would not result in hostile discrimination against the petitioners. ( 18. ) HERE, it is necessary to explain the true concept of ad hoc appointment in service matters. In the present era, in every sphere including that of Services, ad hoc-ism is increasing resulting in frustration and service unrest among employees because of the uncertainty in their service, as the word ad hoc is not being construed in its true sense and is being given altogether a different meaning. In this respect it suffices to say that the meaning of the term ad hoc is a settled one, which means, for any special or particular purpose "or to last for a particular period" (See S. P. Vasudeva v. State of haryana and others, A. IR. 1975 S. C. 2292 (see para 4)) (Emphasis supplied by us ). If special purpose or period is not disclosed in the order making ad hoc appointment, but simply the word ad hoc is mentioned there and the appointee, without any hindrance, is allowed to continue for years together, then by nomenclature of the order (i. e. ad hoc) alone cannot be construed to be an ad hoc appointment, but shall be treated as regular appointment. ( 19. ) THE concept of making ad hoc appointment is that in emergency, regular appointment by conducting examinations and taking interview etc. is not possible due to short of time, then in such event, till regular interviews etc. are taken ad hoc appointment for a special or particular purpose and for a particular period could be made. ( 20. ) NOWADAYS, ad hoc-ism is not being understood in its right perspective resulting in uncertainty in the future of the employees. Therefore, it needs to be curbed. are taken ad hoc appointment for a special or particular purpose and for a particular period could be made. ( 20. ) NOWADAYS, ad hoc-ism is not being understood in its right perspective resulting in uncertainty in the future of the employees. Therefore, it needs to be curbed. Illustratively, suppose, a person who is about 24 years of age, is appointed on ad hoc basis without mentioning the purpose or the period, but only the word ad hoc is mentioned in the appointment order and that such a person is allowed to continue in service for a number of yerars, say 5-6 years and by that time, he crosses the maximum age limit for appointment in Government service and thereafter if his services are terminated on the ground that his appointment was on ad hoc basis, then this narrow approach to the meaning of the word ad hoc will definitely be against the service jurisprudence. ( 21. ) THEREFORE, if no specific purpose or time limit is mentioned in the appointment order making ad hoc appointment, but only the word ad hoc is mentioned and if the employee concerned is allowed to continue in service for years together, then the appointment order will not be treated as on ad hoc basis, but will be certainly liable to be treated as regular appointment. ( 22. ) IN the instant case, the subsequent order changing service conditions after detecting that the petitioners appointments were illegal, specifies the period of tenure of service i. e. upto 30-4-1985 and thus, in our opinion, it fulfils the requirement of ad hoc appointment and is not liable to be quashed. ( 23. ) HOWEVER, Shri Saxena, the learned Deputy Advocate General was fair enough in making categorical statement that though the appointment of the petitioners is ad hoc for a limited period i. e. upto 30-4-85 and they are still continuing in the service on the strength of the ad interim stay granted by this Court, yet they will be given full opportunity to fice interview. As such, in view of the statement of Shri Saxena at the bar, the result of the modified order would be that "all such teachers who had been, given appointment earlier, will be interviewed by the/statutory selection committee and the services of only those who would not be found fit to be appointed as teachers, will be terminated, while the rest will become regular appointees. " ( 24. ) FROM the discussion aforesaid, all the petitions fail and are hereby dismissed. However, in the circumstances of the case, there shall. be no order as to costs. The security amount, if any, shall be refunded to the petitioners. Petitions dismissed.