law: Indian Evidence Act, 1872 
  13. Facts relevant when right or custom is in question 
  Where the question is
  
  as to the existence of any right or custom, the following facts are relevant.
  (a) Any transaction by
  
  which the right or custom in question was created, claimed, modified,
  
  recognized, asserted, or denied, or which was inconsistent with its existence;
  (b) Particular
  
  instances in which the right or custom was claimed, recognized, or exercised,
  
  or in which its exercise was disputed, asserted or departed from.
  Illustration
  The question is,
  
  whether A has a right to a fishery. A deed conferring the fishery on A’s
  
  ancestors, a mortgage of the fishery by A’s father, a subsequent grant of the
  
  fishery by A’s father, irreconcilable with the mortgage, instances in which A’s
  
  father exercised the right, or in which the exercise of the right was stopped
  
  by A’s neighbors, are relevant facts.