PHOENIX >> Miguel Guerra has a wife, three children and a house. He has a car, but no driver’s license. He has business cards, but no immigration papers. He got into the habit of keeping his cellphone close when he drives so he can quickly call a cousin, the only legal resident among his relatives in the United States, in case he gets pulled over.

If he does not call again within an hour, he said, the cousin knows to look for him at the county jail.

Guerra, 36, moved here 13 years ago, before Arizona made illegal immigrants a target, turning once mundane tasks like driving to the grocery into a roll of the dice. Protesting the state’s strict immigration laws “hasn’t changed anything,” he said, so one recent evening he took a more pragmatic approach. He filled out an affidavit designating his cousin to care for his children, his money, his house and everything else he owns should he be arrested.

The Supreme Court is set to hear arguments next week challenging the most controversial sections of an Arizona immigration law, known as SB 1070, which seeks to push illegal immigrants out of the state by making it hard for them to go about their lives and earn a living. Lower courts have prevented many of the most controversial provisions from taking effect, but that has not stopped a chill from seeping into the bones of the state’s immigrants.

“Preparing for the worst is our best defense these days,” Guerra said.

Here and elsewhere in Maricopa County, where one in three residents is Hispanic, illegal immigrants — interviewed at car washes, outside dollar stores, in schools and at the offices of a grass-roots organization called Puente, where Guerra and others worked on their affidavits — seemed almost indifferent to how the Supreme Court will rule on the constitutionality of the law. Having lived through years of relentless enforcement of the state’s anti-illegal-immigration measures by the hard-line sheriff, Joe Arpaio, they feel there is little that can make life harder than it already is.

Guerra said he no longer risked taking his family on road trips to Disneyland in neighboring California.

Maria Jesus, 55, who has a tire store that caters mostly to illegal immigrants, said she was on the verge of bankruptcy because most of her clients had either fled the state or were unemployed and broke.

A man who said he recently spent time in a federal immigration detention center in Florence, Ariz., after he was pulled over for speeding, and who asked to remain anonymous to avoid more legal trouble, says he leaves home every morning afraid he will not come back. (He was freed on bail and has a date in court to decide whether he will be deported, he said.)

Seated across from him at Puente, a woman who would only say that her name was Leticia and that she was 27, interjected: “The people who are home, waiting, are just as afraid. You leave, and we wonder if today is the day you’re going to get arrested.”

The Department of Homeland Security estimated there were 360,000 illegal immigrants in Arizona as of January 2011, the fewest since 2000.

The downturn in the economy, which hit Arizona particularly hard, may offer only part of the explanation for the decline. In 2010, the number of births by Hispanic women fell below the number of births by white women for the first time in seven years, and it continued to fall at least through February, according to state statistics. The drop, 28 percent overall, is too steep to be explained by a decline in fertility rates alone; Jeffrey Passel, a senior demographer at the Pew Hispanic Center, said it may suggest that there are fewer Hispanic women of child-bearing age.

Since the anti-illegal-immigration bill was passed by the state Legislature in May 2010, enrollment at the Balsz Elementary School District here in Phoenix, where 70 percent of the students are Hispanic, has dropped by 8 percent, and fewer parents volunteer to walk groups of children to and from school, the superintendent, Jeff Smith, said.

“We think it’s because they’re afraid of being on the streets,” Smith said.

It has not always been that way. In 2005, when Sen. Edward M. Kennedy of Massachusetts and Sen. John McCain of Arizona unveiled a bipartisan immigration reform bill, which would have provided a path to citizenship to certain illegal immigrants, about 50,000 people rallied here in support. They again took to the streets by the thousands, part of a wave of protests that spread across the country, as SB 1070 made its way through the Legislature.

Their battle quickly moved to the courts, where the bill’s most controversial aspects — like giving law enforcement officers the authority to detain anyone they suspect of being in the country illegally and requiring them to determine the immigration status of people who have been arrested — have polarized the political debate about immigration reform. The Supreme Court’s ruling, whatever it might be, is bound to influence the discussion during the presidential campaign.

A rally has been scheduled here for the day of the Supreme Court’s hearing. Organizers are hoping a few thousand people will turn out; in private, their estimates are less optimistic: 1,000 protesters.

“The excitement of four years ago has turned into bitterness; hope has turned into fear,” said Alfredo Gutierrez, a former state senator and radio host whose call-in show allowed immigrants — illegal and otherwise — to air their feelings in public in the early days after the bill was passed.

The measure “was clearly an attempt to put the entire Latino community under siege, and to a certain extent it has succeeded,” Gutierrez said.

At Puente, the bill was an exclamation point of sorts at the end of one advocate’s long explanation about the other state measures against illegal immigrants: an English-only law in 2002, propositions in 2004 and 2006 that blocked blocking their access to state benefits and their right to post bail, a requirement in 2008 that employers check their workers’ immigration status.

It was Week 3 of Puente’s six-week “defense” course, as one of the organizers put it, the first that the group has offered since opening in 2007 in response to Arpaio’s raids on Latino workplaces and neighborhoods as he looked to arrest illegal immigrants.

“I don’t need SB 1070,” Arpaio said last week from his office downtown. “We’ve been arresting more illegals than we did in the past. We have enough state laws to do that.”

In their wallets, participants in Puente’s course carried a paper that reads, “I will not sign without a lawyer! Slide the warrant under the door!” They also heard other tips: If you have a car, make sure it is registered to someone with a driver’s license. If you have a job, make sure someone knows to collect your pay if you are not around. If you have children, make sure to authorize a legal resident to pick them up at school.

Guerra spoke of friends who had packed up and left — to Utah, Nevada, Washington state — only to come back after finding no jobs or running into laws much like the one that drove them from Arizona.

“So here I am, getting ready for what’s to come,” he said.