Thankfully, all is now well, as they've settled the suit and Otero County has completely knuckled under to the demands of the two illegal immigration-supporting groups, establishing sanctuary city-style procedures that are available here:
aclu-nm.org/PDF/SOP4_9_08.pdf
While some are defensible, Point B contains what is probably a false statement: "A person's presence in the United States without proper documentation or authority, standing alone, is not a criminal violation." In fact, re-entering illegally can be a felony in some cases, and I'd imagine that applies to their presence as well. While some provisions of the agreement may prevent actual abuses, no doubt others will be used to tie their hands and prevent them from reasonable attempts to take a role in immigration enforcement.
UPDATE: Since Findlaw is a reputable site that probably keeps their pages up-to-date, I'm going to assume that this is accurate, meaning that Point B above is misleading:
After an alien has been legally "removed" from the United States, federal criminal law makes it a felony for that alien to reenter (or be found in) the country without approval of the government.
Presumably "legally removed" doesn't apply in many cases, and in any case someone has to decide to prosecute them for the felony; see the cases of the fired U.S. attorneys Paul Charlton and Carol Lam (link).
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