B. SUBHASHAN REDDY, C.J. :--The question in this batch of writ petitions and connected writ appeal is whether the doctrine of legitimate expectation, which is a judge-made law, can be invoked to assail the changed Government policy relating to improvement examination as promulgated in G.O. Ms. No. 142, School Education Department, dated 12-9-2001.

2. We may have to go to the genesis of the said Government Order, which is impugned in this batch of writ petitions. Henceforth, the said G.O. Ms. No. 142, dated 12-9-2001 will be referred to as the impugned G.O.

3. The Government of Tamil Nadu evolved a scheme enabling the students to re-appear in the Higher Secondary Examination for improvement called 'improvement examination'. That was introduced for the first time, by issuance of G.O. Ms. No. 1457, Education Department, dated 7-10-1989. It is needless to mention that the said Scheme has been evolved in exercise of the State's executive power under Article 162 of Indian Constitution. The Scheme for the Award of Higher Secondary Course Certificate was introduced in 1978 and the first batch of Higher Secondary candidates appeared for the examination in March 1980. Before the issua