law: Marine Insurance Act, 1963 
  86. Implied obligation varied by agreement or usage 
  (1) Where any right,
  
  duty, or liability would arise under a contract of marine insurance by
  
  implication of law, it may be negative or varied by express agreement, or by
  
  usage, if the usage be such as to bind both parties to the contract.
  (2) The provisions of
  
  this section extend to any right, duty, or liability declared by this Act which
  
  may be lawfully modified by agreement.