In Canadian, English and Australian law at least, there is
an equitable principle known as estoppel. I believe the
same concept arises in American law.
I believe that modernly this exists in U.S. law primarily, if not
only, in areas relating to contract, and I think that anyone would be
hard pressed to classify this as a contract situation. I'm fairly
certain that it does not apply in the patent arena. I'm *certain*
that the patent bar is not one of equity, although of course post
patent approval you then end up in a Federal court to litigate
infringement claims.
Anne