They are essentially inadmissible as evidence (this is apparently not quite that clear cut, but as far as I can tell, it'll do for our discussion) but it is not

They are essentially inadmissible as evidence (this is apparently not quite that clear cut, but as far as I can tell, it'll do for our discussion) but it is not disallowed as a post-conviction measure. Apparently, once you've been convicted, the laws of logic magically stop applying to your situation.