The Final Grat Regulations : Schott Shot Down

The problem, here, with accepting successive spousal interests is not that a dual life interest is any more contingent or unreliable a term measurement than a single life interest, which is acceptable under the regulations. Rather, the difficulty is produced by the fact that the spousal interest is contingent on the grantor's power to revoke, which, controllable by the grantor, may make that interest an illusionary one. The regulations treat a revocable spousal interest as the grantor's interest as if it were identical to the grantor's life interest. While one can reason that because a grantor's revocable power becomes irrevocable at his death, the term is actually for the grantor's life; inevitably, however, it is that departure from the general rule against contingencies that undermines the rationale for the prohibition against contingencies and causes the distinctions later drawn to be somewhat capricious