the 1978 Act was substituted. As per the earlier rules, the reservation was on the vacancy based and after the amendment it was post based reservation. The respondent authority on the basis of wrong interpretation of the said amendment erroneously worked out showing the reserved posts meant for ST(H) were fully utilized giving retrospective effect of the amended provision of the Act inasmuch as the amendment came into force with effect from 21.08.2012. Prior to 2012 the reservation policy was against the vacancy based reservation and as such the required percentage of reservation ought to have been calculated on the basis of the vacancies of posts sought to be filled up by the authority on the resultant vacant posts after 21.08.2012. As per model 100 point roster the ST (H) incumbent is earmarked at post No. 10, 30, 50, 70 and 90. Even in the said post based roster also the ST(H) incumbents are at least entitled 5 post in ACS (Jr. Grade) but the respondent authority in the advertisement indicated there was no reservation post for ST(H) and SC categories for the post of ACS (Jr. Grade) due to full utilization of the prescribed percentage of reservation. There is arbitrariness in the action of the respondents to deprive the petitioners inasmuch as the amendment and the substitution in the Act 1978 has no retrospective effect and as such the roster point reserved post in services sought to be filled up by the advertisement on the basis of vacancies of post after 21.08.2012 is an arbitrary act on the part of respondents.