Benefits acquired under existing rules cannot be taken away by amending the rules with retrospective effect, and retrospective application of a scheme leading to denial of rightful benefits is arbitrary, unconstitutional, and violative of fundamental rights.

1. Whether the applicability of the Modified Assured Career Progression Scheme ("MACP Scheme" for short) to the petitioners with retrospective effect from 1.9.2008 is violative of Articles 14 and 16 of the Constitution of India is the question that falls for consideration in this batch of writ petitions.

2. Briefly stated the facts are as follows:-

The Petitioners joined the Military Engineer Services, Ministry of Defence, Government of India as civilian employees and are working as such to this date. The details of their joining the services and the date on which they had completed 24 years of regular service are noted in the following table.

Sl. No	Name of the Petitioners with MES No	Date of joining the services & the post	Date on which the Petitioners have completed 24 yrs of regular service.
1.	B.D. Kadam – 600051	29.04.1985 Suptd. E/M. Gr.II (Initial)	29.04.2009
2	Balakrishna Raju – 127664	01.04.1985 Suptd.B/R. Gr.II	01.04.2009
3	P.M.Jain – 188656	02.05.1985 Suptd.B/R. Gr.II	02.05.2009
4	P.Abdulla – 123542	26.04.1985 Suptd.B/R. Gr.II	26.04.2009
5	V.M.Vantamutte-124485	08.04.1985 Suptd.E/M. Gr.II	08.04.2009
6	P.R.Raju – 124483	04.04.1985 Suptd.B/R. Gr.II	04.04.2009
7	Sri.S.Mani Mohan 127665, A.E. (Civil)	01.04.1985 Suptd.E/M. Gr.II	01.04.2009
8	Smt.P.Sumathy-134938J.E.(QS & C)	01.04.1985S.A.-II	01.04.2009
9	Smt.JayashreeJayakrishnan-190730J.E. (QS & C)	01.04.1985S.A.-II	01.04.2009
10	Smt.Valasala Kumari-187889, A.E.(Civil)	02.04.1985Suptd.B/R. Gr.II	02.04.2009
11	Smt.Kumari N.P.109773, A.E. (Civil)	03.04.1985 Suptd.B/R. Gr.II	03.04.2009
12	Sri.P.Sur Reddy-194632A.E.(Civil)	08.04.1985 Suptd.B/R. Gr.II	08.04.2009
13	Sri.S.Sounderarajan-128077, J.E. (QS & C)	11.04.1985S.A.-II	11.04.2009
14	Sri.P.H. Abdul Kareem- 188615, A.E.(Civil)	15.04.1985Supdt. B/R. Gr.II	15.04.2009
15	Sri.DSRK Reddy 123729, A.E. (Civil)	02.05.1985Supdt. B/R Gr.II	02.05.2009

3. It is not in dispute that the petitioners have completed 24 years of continuous service in the same post without any promotion and by virtue of Assured Career Progression Scheme ("ACP Scheme" for short) which was in vogue, all the petitioners were eligible for grant of II-ACP on completion of 24 years of continuous service. But before consideration of the case of the petitioners for grant of the said benefit, MACP Scheme was introduced by the Government vide Office Memorandum dated 19.5.2009 and the same was made operational with effect from 1.9.2008. As all the petitioners had completed 24 years of continuous service during the interregnum between 31.8.2008 and 19.5.2009, the petitioners challenged the efficacy of making the MACP Scheme operational retrospectively on the ground of violation of Articles 14 and 16 of the Constitution of India, before the Central Administrative Tribunal ("Tribunal" for short).

4. The Tribunal, after hearing both the parties, by a common order in O.A.Nos.1086-1091 of 2014 and 897-905 of 2015 dated 10.3.2016 dismissed the claim of the petitioners.

5. The reasoning assigned by the Tribunal to uphold the retrospective applicability of the O.M. dated 19.5.2009 finds place in para 20 of the impugned order. It is extracted herebelow:-

"20. Under the previous ACP Scheme, Financial upgradation was to be given to the next higher grade in accordance with the existing hierarchy in a cadre or the category of the posts without creating a new post for the purpose. On the other hand in case of MACP, it envisages placement in the immediate next higher grade pay in the hierarchy of the recommended revised pay band and grade pay as given in Section-1 in part A of the first schedule of CCS (Revised Pay) Rules 2008. It is to be noted t