Delimitation is the process by which the boundaries of electoral constituencies, whether for the Lok Sabha, state assemblies or even local bodies, are periodically redrawn. A democracy ideally operates on a one-man-one-vote principle. However, since the voter in India directly elects only the MP or the MLA representing his or her constituency, for this principle to be translated into practice, constituencies must have roughly equal populations. Otherwise, each voter in a smaller sized constituency would have a greater voice than one in a larger constituency.
As populations in different places change naturally and as a result of migration patterns, the actual number of people living within the boundaries of any constituency keeps changing. Unless constituencies are regularly redrawn, the chances are that they will become unequal in size over time. For instance, the Outer Delhi Lok Sabha constituency had an electorate of almost 34 lakh in the 2004 elections. Lakshadweep, on the other hand, had an electorate of just over 39,000. Yet, both elect one MP each to the Lok Sabha, which means that every voter in Lakshadweep was equivalent to around 86 voters from Outer Delhi. It is to avoid this kind of situation that constituency boundaries need to be periodically redrawn so that as far as possible each MP in the Lok Sabha represents the same number of citizens.
This is also a constitutional stipulation. The Constitution (under Article 81, Section 2) stipulates that each state will, as far as practicable, be allocated seats in the Lok Sabha in proportion to its share in the population of the country and that each constituency within a state should also be determined on the same basis.
If Lok Sabha constituencies were to be made strictly equal in terms of the size of the population, it would mean either an enormously large House or that some states and Union Territories would go unrepresented. If, for instance, Lakshadweep was taken as the yardstick and we had a Lok Sabha MP for every 39,000 of the population, then the total size of the Lok Sabha would have to be around 28,000! On the other hand, if the size of the Lok Sabha is to remain at 543 elected members, this would mean no seats for Lakshadweep, Andaman and so on. Hence, Parliament amended the Constitution in 1973 — Thirty-First Amendment — to provide that states with a population of under six million would not be governed by the rules regarding seat-allocation applicable to other states. This means that smaller states and UTs are effectively overrepresented in the Lok Sabha, but this was considered a lesser evil than leaving them out altogether.