Supreme Court in the case of Subhash Chandra vs. Mohammad Sharif & Ors. reported in AIR 1990 SC 636

“Doctrine of estoppels ordinarily applies where the tenant has been let into possession by the plaintiff. Where the landlord has not himself inducted the tenant in the disputed property and his rights are founded on a derivative title, for example, as an assignee, donee, vendee, heir, etc., the position is a little different. A tenant already in possession can challenge the plaintiffs claim of derivative title showing that the real owner is somebody else, but this is subject to the rule enunciated by Section 116 of the Evidence Act. The section does not permit the tenant, during the continuance of the tenancy, to deny that his landlord had at the beginning of the tenancy a title to the property. The rule is not confined in its application to cases where the original landlord brings an action for eviction. A transferee from such a landlord also can claim the benefit, but that will be limited to the question of the title of the original landlord at the time when the tenant was let in. So far claim of having derived a good title from the original landlord is concerned, the same does not come under the protection of the doctrine of estoppel, and is vulnerable to a challenge. The tenant is entitled to show that the plaintiff has not as a matter of fact secured a transfer from the original landlord or that the alleged transfer is ineffective for some other valid reason, which non-existent in the renders the transfer to be eye of law. By way of an illustration one may refer to a case where the original landlord had the right of possession and was, therefore, entitled to induct a tenant in the property but did not have any power of disposition. The tenant in such a case can attack the derivative title of the transferee-plaintiff but not on the ground that the transferor landlord who has initially inducted him in possession did not have the right to do so. Further since the impediment in the way of a tenant to challenge the right of the landlord is confined to the stage when the tenancy commenced, he is not forbidden to plead that subsequently the landlord lost this right. These exceptions, however, do not relieve the tenant of his duty to respect the title of the original landlord at the time of the beginning of the tenancy”.

ONUS OF EVIDENCE : In a case where the defendant in a suit for eviction denies the plaintiffs derivative title to the suit property, the onus is on the defendant to show that the plaintiff has not, in fact, derived any title in respect of the suit property from the original landlord.