While words like "allegedly" should be avoided, it is even worse to word a proposition by "it is". Instead, you should write like "Who-and-who suggested that...". yck C. 

Dorvaq, thank you for the pointer, where I see "Newspapers, for instance, almost universally refer to any indicted but unconvicted criminal as an alleged criminal."  Agreed; I use 'alleged' whenever writing about someone where crimes have been charged but not yet proven in a court of law.  Perhaps what I'm trying to ask is more of a common-sense question to which the answer is so obvious that no one has thought to incorporate it in a policy or guideline here.  Trying again, "Once an accused criminal is convicted in a court of law, is it not both inappropriate and biased to insist on using the word 'alleged' when writing about the charges of which he's been convicted?"  Maybe someone has a pointer to an old discussion or arbitration about this?  It seems that it must have come up in the past.   
I'm pretty sure there is no discussion involving the generic use of "allege" (or any derivative thereof) specific to before-and-after trials.  However, there has been many discussions of this sort on individual article pages involving criminals. But, most of these discussions have been initiated by either anonymous users or users who contribute very little to Wikipedia besides the article in question.  Perhaps your best bet would to start there unless someone else can provide you with something more informative.

Anyhow, I don't believe this needs to be incorporated into policy/guideline beyond how the word has already been treated.  In terms of law, to allege is to present without proof or without first proving.  Therefore, to state the convicted crime of an offender as an allegation is inherently contradictory. Wikipedia is dedicated to quality and integrity — anything contradictory fails on those two points, but that's my opinion. —  (talk) 

Ah, that last paragraph hits the nail on the head, thanks.  Nothing like logic to prove a point.  I came upon the Megan Kanka article by chance and I remember the case quite well.  It really irked me, after removing all the 'allegeds' and cleaning up the article, to find an old entry on the Talk page stating "He argues that he was wrongfully convicted; if he admitted to the allegations, they wouldn't be alleged, but he hasn't, so therefore they're 'alleged,' and he's the 'alleged killer.'"  Arrgh!  Thanks again.