Here's a phrase I just spotted in a (generally very good) paper I'm reading:
[T]he Court has sanctioned the use of speech as evidence in establishing that ....
Is that "sanctioned" in the sense of "approved" or in the sense of "punished" (a common use of the term "sanction" in litigation)? The reader should be able to figure this out from context, but it's usually better not to put the reader to the work of having to do that, or risk even briefly leading the reader in the wrong direction.
So be careful with this contronym, and avoid using it as a verb, except when the context makes things completely clear (for instance, because you have just been talking about Rule 11 sanctions -- a common legal term -- and your use of "sanctioned" clearly links back to the earlier noun phrase).