illegal immigration Entering or residing in a country in violation of civil or criminal law. Except in direct quotes essential to the story, use illegal only to refer to an action, not a person: illegal immigration, but not illegal immigrant. Acceptable variations include living in or entering a country illegally or without legal permission.
Except in direct quotations, do not use the terms illegal alien, an illegal, illegals or undocumented.
It may seem like a subtle distinction, but it's really not. Labeling a person as an "illegal" serves to dehumanize them eyes of the reader. There's a great episode of Slate's podcast Lexicon Valley that addresses the topic in depth. Well worth listening.
So yeah, this is a big deal. And a big step toward a more rational immigration debate.
Also of note, especially in the context of the debate over both our state and federal Dream Acts, is the following extra bit of instruction from AP's editors: "People who were brought into the country as children should not be described as having immigrated illegally." Because, you know, to do so would be to imply that the children were culpable for an act over which they had zero control.