Necessitas juris is a Latin termwhich means ‘by necessity of law’. It arises necessarily from the nature or effect of legal rules. For example, a creditor may sue his debtor for the rents or dues outstanding in a court of law. The debtor himself and no other one will be liable for his/her debt. If the debtor dies in the mean time and his successor succeeds to his estate, the creditor can go after him for the debts owned by his predecessor to the extent of the assets held by the debtor as if s/he is liable for the debts. Thus the rule of necessity makes it obligatory on the part of the creditor to sue the debtor’s successor to realize his debts as if the successor himself had availed the loan.