Doctrine of Pious Obligation means the moral liability of sons to pay off and discharge their Father's Non-Avyavaharika Debts.
Non-Payment of debts is a sin and also a crime.Any person,who died leaving the debts behind cannot go to Heaven.The "Putra" i.e. the son,sons's son and son's son's son by repaying or clearing off such debts,discharges his parted father or ancestor from the indebtedness and enables facilities him to reach the Heaven. This duty or obligation of a son to repay the debts of the deceased father(parter ancestor) is rested upon a special doctrine,known as "The Doctrine of Pious Obligation".However this obligation extends to Non-Avyavaharika (or vyavaharika) debts only.Avyavaharika debt is one,which is taken for illegal or immoral purpose.Eg:-Gamling,Races etc.
Under Old Law ,the doctrine(obligation to discharge the debts)arises after the death of the father.But,according to the Modern law the obligation arises even during the life time of the father.Further,Under the Old Law,the son had an obligation to pay the debts with interest.The Grand son was liable for the principal amount only.The great gand son was not liable ,unless he had received the property from the ancestor.But,according to the Modern Law all son,sons's son and son's son's son are liable to pay the debts with interest.
When the father being the Karta of a Hindu Joint Family contracts a loan for legal necessity,the loan is binding on all the members of the Joint Family.If he incurs debts for his personal purpose,he is personally liable.To clear off such debts,he may have to alienate his personal property or his sons's property.In case his son's property is alienate,his son should not questioned him.
Debts outside the Scope of the Doctrine:
Commercial Debts:
Commercial Debts was regarded outside the doctrine, according to Old law.To the present law,it is within the doctrine.(i.e.the son is liable to pay the commercial debts)
Suretyship Debts:
Liability arising out of suretyship by the father is not binding on his son.Hence,it does not come within the doctrine.
Gaming Debts:
Gaming Debts are outside the doctrine as per the Old and New laws.Eg:Debts incurred for drinks,liquors etc..
Avyavaharika Debts:
According to the Mitakshara,it is outside the doctrine.Cole brook translated it as "a debt for a cause repugnant to good morals".In other words,it is a debt for an illegal or immoral purpose.