When Arizona's new immigration law goes into effect next month, every immigration check performed by the state's 16,000 officers will be under a microscope.

The law requires an officer to determine a person's immigration status if they are stopped, detained or arrested and there is "reasonable suspicion" they are in the country illegally.

Organizations, such as the League of United Latin American Citizens, say they will be ready to sue immediately if they feel citizens were questioned improperly.

To head off such issues, a group of a dozen people are poring through court opinions and researching identity documents to establish training for each of the state's police officers.

Lyle Mann, director of the Arizona Peace Officer Standards and Training Board, said each department will receive a video, handouts and a brochure that explains the basics of identity documents such as passports and green cards.

An agency can expand the training with a talk by its chief, sheriff or legal adviser.

Mann said officers will be trained to identify illegal immigrants in the same way they develop reasonable suspicion for any other criminal offense - by piecing together different factors.

"Officers live reasonable suspicion every day," Mann said.

He used the example of a routine traffic stop where the driver lowers the window and the smell of marijuana smoke is present. The person was pulled over on a reasonable suspicion of speeding, but the smell of marijuana created a reasonable suspicion that the person has drugs.

"That's no different than the process that an officer will go through with the question of (suspects) being in the country legally or illegally," Mann said.

Hipolito Acosta, who used to oversee Latin America for the Immigration and Naturalization Service, said there are many small factors that can be used to reach that reasonable suspicion:

• A person wearing many layers of clothing on a hot day in Phoenix could indicate he just crossed the border in the desert, where it gets very cold at night, Acosta said.

• A person acting nervously and avoiding eye contact during a simple traffic offense.

• Children present in a house under a search warrant who are not going to school and are not related to the adults in the house.

• A person who inexplicably runs when an officer approaches a gathering of day laborers.

"Individuals in the country legally are not going to be afraid of a law enforcement officer approaching," said Acosta, who is helping Arizona develop its training program.

Critics of the law, including the National Council of La Raza, a Hispanic civil rights group, argue that officers will undoubtedly use people's appearance to create a reasonable suspicion.

Police officials say it's insulting to think that all officers will racially profile.

"Will there be a rogue cop out there who wants to racially profile? That may be true," Mann said. "But he or she will be treated like anyone else who fails to follow policy or procedure."