Hungry estoppel? Worry not, I'll feed you. Feeding the Estoppel

GOR without legal interest in land grants it to GEE. As between GOR and GEE, GOR is estopped from disclaiming the grant owing to lack of interest. GEE as against GOR has a right in personam, (ie, not against the world).

When thereafter GOR gets legal title to the land, the estoppel is fed. The original grant takes effect by interest and not just by estoppel. GOR is of course estopped from disclaiming his original lack of title. But at this point, where the estoppel is fed, GEE’s interest is good against the world. His rights are in rem. As noted, before dinner, GEE’s interest is good only against GOR.

Put another way, a grantor purports to grant an interest in land, which interest he or she did not at the time have. The grantor subsequently acquires the interest. The benefit of the subsequent acquisition goes automatically to grantee. The subsequent acquisition feeds the estoppel.