New Haven’s controversial immigration raids may be a symptom of a simple, but momentous, political change at the federal Immigration and Customs Enforcement agency.

A report released by the Migration Policy Institute this month highlights a crucial policy shift that created an incentive for ICE agents to detain as many illegal immigrants as possible, rather than focus on high-priority, criminal targets. And while it is unclear what impact this policy shift had on New Haven, in particular, this has not stopped city officials from continuing to scrutinize ICE raids.

ICE conducted a raid in the New Haven area last month — its first since its controversial Fair Haven raids two years ago, when just four of the 31 immigrants detained had deportation orders. Community leaders accused ICE of retaliating against the city’s Elm City ID program (which, among other benefits, provides a picture identification regardless of immigration status) and terrorizing the immigrant population with dragnet raids. Federal officials maintained that the raids were routine.

But the real reason behind the controversial raids may lie in ICE’s 2006 policy change, which altered the definition of what constitutes a routine raid.

Before 9/11, there was no such thing as ICE — the Immigration and Naturalization Service and the Customs Service were two separate entities. But after the September attacks, when it was discovered that several of the hijackers had been in the United States illegally on expired visas, Congress and the 9/11 Commission emphasized the importance of a coordinated effort to find and remove fugitive aliens.

In 2003, the Bush Administration created ICE, which, under its newly formed parent agency, the Department of Homeland Security, began aggressively targeting illegal immigrants. But not all immigrants were deemed equal. In a Jan. 22, 2004, internal memo, the head of ICE’s Detention and Removal Office, Anthony Tangeman, told agents they must prioritize whom to target. They were to go after criminals.

“No less than 75% of all fugitive operation targets will be those classified as criminal aliens,” he wrote.

Immigrants without criminal records would not count toward fulfilling each team’s arrest total.

But on Jan. 31, 2006, a new director, John Torres, eliminated the 75 percent criminal requirement and drastically increased the desired number of arrests — to 1,000 from 125 per enforcement team. At first, non-fugitive aliens were still not counted toward that goal. But on Sept. 29 of that year, Torres lifted even that restriction: “Non-fugitive arrests may now be included in the total,” he wrote.

It was this last shift that was the most decisive, argues the nonpartisan Migration Policy Institute in a recent report. By increasing the quota and including noncriminals in it, ICE agents had little incentive to prioritize criminal targets.

“This was not the original goal of the program,” Shayna Strom, co-author of the report, said in a telephone interview. “This pressure, and quota, reduced the ability to get criminals.”

New Haven officials have even stronger criticisms of the policy. Kica Matos, New Haven community services administrator and designer of the Elm City ID card, said this was inexcusable.

“They tell Congress they’re prioritizing, but they’re getting all these incidental arrests,” she said. “Enforcing the law is no excuse; it’s immoral, unethical and unconscionable.”

But ICE Spokesman Richard Rocha defended the policy, saying it was well in accordance with the agency’s mission.

“The number of arrests is a goal, not a quota, and we do prioritize,” he said. “But if, in the course of our work, we encounter other illegal individuals, we have to enforce the law.”

And, he added, it is important to note that in 2008, arrests of individuals with criminal records had increased by 179 percent.

The biggest numerical increase has been in ICE fugitive teams’ budgets. From 2003 to 2008, funding increased 2,400 percent, from $9 million to $218 million. And indeed, criminal arrests have risen, but only in the last year. Until 2008, the number of criminals arrested stayed flat, while total arrests skyrocketed. Even with the recent increase, noncriminals represent the great majority of arrests.

Alexandra Dufresne, immigration policy expert and lecturer in the Yale Political Science Department, believes ICE’s strategy uses government resources inefficiently and inhumanely. She cited the high costs of detaining immigrants on minor charges and the absence of a right to a government-appointed lawyer as major obstacles.

“Many noncitizens do have valid defenses to deportation, but being detained makes it nearly impossible for them to prevail on otherwise viable claims,” she said. “Detention is also a frightening and dehumanizing experience, particularly for people who find themselves in jail but who have never committed a crime.”

She added, “There are more humane, just and cost-effective ways to enforce our nation’s immigration laws.”

The new Homeland Security Secretary, Janet Napolitano, has ordered a complete review of ICE’s enforcement operations.