The efficacy and practical relevance of the solution of any technical problem depends not only upon effective formulation of an objective function, but also on the choice of constraints, which limits the solution space, and same is the case with distribution network expansion planning (DNEP) problems as well. The objective functions of DNEP problems need to be bound by appropriate technical, social and economic constraints to arrive at the optimal solution for any site. Constraints are the conditions imposed in DNEP on various objective functions to achieve the most cost-effective, consistent and environment-friendly optimized solution. Hence the choice of appropriate constraints has a significant role in the execution of DNEP problems effectively. The present work aims to summarize the constraints considered in more than eighty selected original articles published over a decade. The constraints considered by various eminent researchers have been discussed by classifying them into technical, non-technical, time & financial and miscellaneous constraints. Special considerations required for deciding constraints for DNEP concerning assimilation of distributed generation (DG) and distributed energy storage system (DESS) have been discussed as well. The summary of constraints, through comprehensive review of the gigantic volume of literature on DNEP published over the past decade will help enduring and budding researchers in this field, pinpointing any breaks in reviewed literature that can be address in impending research for further enhancement and can be employed to arrive at an optimum solutions to DNEP problems.