See Fr. Z’s entry here: http://wdtprs.com/blog/2012/03/fr-guarnizo-has-more-to-say-about-being-removed-from-ministry-in-washington-d-c/
Update: If you have a problem with Dr. Peter’s analysis, find his e-mail and take it up with him and don’t tell tales out of school here please.

It’s frustrating to read comments about this case wherein writers complain
about Dr. Peters and his opinions. I’ve yet to read one such complaint
where the writer mounted a logical, dispassionate argument against Dr.
Peters’ conclusions. Instead, the complaints all seem to be variations on
the themes of “I don’t like what he says, I don’t like what he says Canon
Law says, if Canon Law says this then it’s wrong”.
My sympathies lie with the good Father Guarnizo. From what I can tell
about this matter (and I have no first hand knowledge), the archdiocese
has acted badly. But was Fr. Guarnizo acting completely in accord with
Canon Law that day? Dr. Peters says he does not seem to have, and I
have yet to see his opinion refuted.
Hmm. Well, I hope you won’t count this as “telling tales out of school,” but let’s try a thought experiment. Imagine that the U.S. slides further into debauchery and that pedophilia is legalized. Now imagine that a man shows up at his mother’s funeral mass with a 7-year-old boy in tow, whom he introduces with a proud smirk to some target Fr. G., before the service, as, “My boy lover (isn’t he beautiful?).”
Based on this learned analysis of canon law that we are hearing about, is this hypothetical Fr. G. breaking canon law if he refuses to give the Sacrament to this man when he approaches the rail?
I trust that’s a sufficiently dispassionate argument.