Federal immigration authorities quietly announced a new policy just before Christmas that promises to ease conflicts with local law enforcement agencies while targeting violent criminals for deportation. The new Immigration and Customs Enforcement agency policy mirrors what was promised four years ago when the Se Communities program was launched. ICE will review fingerprints from people arrested by local police, and it will seek custody of people believed to be in the United States illegally if they have committed a serious crime or are repeat offenders. In practice, ICE has detained and deported thousands of people with no criminal record or who have been arrested for petty offenses such as traffic violations. In Sonoma County, 47 percent of the people turned over to immigration agents in the first year of the program hadn’t been convicted of the crimes that landed them in jail.