The VASRD is governed by principles that dictate how the Rating Authorities should assigned Military Disability Ratings in various circumstances. These principles are meant to make up for any shortcomings or holes in the rating schedule and to create equality and fairness when applying the ratings. Some principles are specific to single conditions (these will be discussed on the individual condition pages), and some can be applied to all.

The principles in the VASRD were originally meant to govern only VA Disability cases, and so when the VASRD began being officially used for DoD Disability as well, the DoD had to make a few changes to the principles in order to apply them successfully in the DoD system. Everything below applies to both the DoD and the VA unless it is clearly stated.