According to this maxim, if a person is involved in illegal activity then he/she cannot sue another for damages that arises out of that illegal activity. The best example of this principle can be an injury to a person, who is driving a stolen car (the person is aware about the fact that the car is stolen). This maxim applies not only to tort law but also to contract, restitution, property and trusts.  The rationale behind this principle is that it would be wrong to allow a criminal to profit from a crime committed by him/her. This principle is one of the widely used by the lawyers of the defendant party as it allows the defendant to escape his liability even though he is guilty of an unlawful act.
‘N’ entered into a contract with ‘B’ for the supply of 10 kg Cannabis on 10th June 2018 for a consideration of Rs. 20,000. ‘B’ failed to supply the cannabis, as a result of this ‘N’ sued ‘B’ for the breach of contract. The court held that it was an immoral contract and hence cannot be enforced.
Indian Law Position:
In India also the above-mentioned principle is widely used by advocates of the defendants. However, there are two exceptions to this principle.
1) In the case of Agents and Trustees, this defense is not available where they are holding the property for another person even if the purpose for which the property is to be used is unlawful.
2) If the illegality is of so trivial nature that the plaintiff does not need to rely upon it for his case. Denying him to recover the damages in such cases would be against the public policy.
Legislative Assembly of ‘XYZ’ country passed an amendment in existing law which increased the penalty for committing the offence of ‘Drink & Drive’ to 10 years imprisonment from 5 years imprisonment. In this case, all those who were found to be guilty of committing the offence of ‘Drink & Drive’ before the passing of the amendment will be punished as per the earlier law and have to go through imprisonment for 5 years. Applying the amended law on them would be having ex post facto effect which will violate Article 20(1) of the Constitution of the ‘XYZ’ country.
I.T.C. Limited v. George Joseph Fernandes & Anr.
In the above mentioned case the principle of Ex turpi causa non oritur action was applied. In this case, Honorable Supreme Court provided that –
“A contract which was not illegal from the beginning may be rendered illegal later by the method of performance which did not comply with the statutory requirements. The appellant’s burden was to show that the charter party was illegal to take it out of the arbitration clause for if the contract is illegal and not binding on the parties the arbitration clause would also be not binding. Once it is shown to have been illegal it would be unenforceable as ex turpi causa non oritur action”. 
M.D., Army Welfare Housing Organization v. Sumangal Services Pvt. Ltd
In the above-mentioned case also the principle of Ex turpi causa non oritur action was applied. 
Lane v. Holloway
This case is also one of the most famous cases related to this principle. In this case an old gardener who had disputes with a café owner. One day the gardener shouted abusive words at the wife of the café owner. Due to this defendant stood up from his bed and went outside. The gardener thought that he was about to be hit by the café owner and therefore punched the café owner. The café owner retaliated and punched him in the eyes which caused him grave injuries. The café owner claimed that due to ex turpi causa non oritur action he cannot be held liable. The court ruled in the favor of the garden owner by providing the rational that the punch by the café owner was of greater proportion than the proportion of the punch by the garden owner therefore there was no ex turpi causa non oritur action.
Edited by Vigneshwar Ramasubramania
Approved & Published – Sakshi Raje
Turpi Causa Non Oritur Actio, I PLEADERS (20th May 2019), https://blog.ipleaders.in/ex-turpi-causa-non-orituractio/.
 I.T.C. Limited v. George Joseph Fernandes & Anr., 1989 AIR 839. 26
M.D., Army Welfare Housing Organisation v. Sumangal Services Pvt. Ltd., Civil Appeal No. 1725 of 1997.
Lane v. Holloway, 3 WLR 1003.