Literal MeaningIn a dead hand.
The property of religious corporations could be said to be “in dead hands”, as the members of such corporations were considered civilly dead after taking religious oaths.
In mortua manu is a Latin term which means in a dead hand. Mortmain means thus “incapacity of selling possessions or estates”. The Origin of the term is to indicate that a person who had died years earlier still dictated land use to the next generations by leaving it to the Church, which never died, and hence never had to relinquish land.
Property owned by religious societies was said to be held in mortua manu, or in mortmain, since religious men were civiliter mortui.
In Morelle LD v. Waterworth, observed that a foreign company which doesn’t establish any business of office and does not register itself in any way is a modern instance of a dead hand (mortmain) for it puts itself in a position, if not to defeat its obligations entirely, at least to make it most difficult for dues to be collected from it.
Edited by Vigneshwar Ramasubramania
Approved & Published – Sakshi Raje
Reference: 1B1. Comm. 479; Tayl. Gloss  Morelle LD v. Waterworth,  3 WLR 257.