Section 28A(7) in The Rajasthan Police Service Rules, 1954
(7)Selection for promotion to the highest post/posts in the State Service shall always be made on the basis of merit alone:Provided that-(a)in a Service Groups or Sections thereunder, where there are only two scale e.g. junior scale or senior scale and there is only one promotion then promotion shall be made on the basis of seniority-cum-merit alone.(b)in a Service or Groups or Sections thereunder, where there are three scales e.g. junior scale, senior scale and selection scale and there are two promotions then promotion shall be as under:-(i)first promotion on the basis of seniority-cum-merit.(ii)second promotion on the basis of seniority-cum-merit and merit in the proportion of 50:50.(c)in Services or Groups or Sections thereunder, where there are more than two promotions then first promotion shall be made on the basis of seniority-cum-merit alone and promotions to subsequent higher posts shall be made on the basis of seniority- cum-merit and merit in the proportion of 50:50 except to the highest post.Provided further that if the Committee is satisfied that suitable persons are not available for selection by promotion to highest post/posts strictly on the basis of merit in a particular year, selection by promotion to highest post/posts on the basis of seniority-cum-merit may be made in the same manner as specified in these Rules.