Police who patrol Los Angeles’ airport and port were barred from enforcing federal immigration laws Tuesday, as Mayor Eric Garcetti signed an executive directive ordering them to follow policies embraced by the Los Angeles Police Department.

The order aligned the officers with Special Order 40, which was issued in 1979 and prohibits inquiring about a person’s immigration status during a law-enforcement action or arresting someone for specifically violating immigration laws.

“We’re taking a big step forward, expanding these policies to our other police departments in Los Angeles,” Garcetti said, just before signing Executive Directive 20 at the Lincoln Heights Youth Center Complex.

“If you’re in the business of protecting and serving people … you should be protecting all people without regard to their immigrant status,” he said.

Garcetti said the directive is an attempt to stop immigrant residents in Los Angeles from shrinking into the shadows. He noted that amid a climate of “policies, executive orders and rhetoric that are divisive, mean-spirited and often unconstitutional,” there are now “less people reporting crimes” or participating in public life.

Los Angeles Port Police Chief Tom Gazsi said the order wouldn’t pave a new path for his officers. “Our policies and practices are consistent with Special Order 40,” Gazsi said. “L.A. port police officers don’t engage in immigration inquiry based on immigration status solely. Our contacts are based on probable cause that a violation of state or municipal laws occurred,”

The Los Angeles Fire Department will adopt similar rules.

The executive directive also refers to other LAPD policies, such as not participating in 287(g), in which local authorities are deputized to carry out federal immigration laws, and not honoring Immigration and Customs Enforcement detainers without a warrant.

“LAPD has never participated in programs that deputize local law enforcement to act as immigration agents, and on my watch they never will,” Garcetti said.

The LAPD in 2014 stopped honoring ICE detainers “without a warrant signed by the court,” Garcetti said.

The mayor was joined by LAPD Chief Charlie Beck, who said his officers have “never been involved in enforcing civil immigration law — and we never will.”

Beck said having police enforce immigration laws hurts the department’s relationship with the community.

“Those (relationships) are not sustained when a police department knocks on the front door to get witness information and to talk to a victim, and people run out the back door,” Beck said. “And that is what we fear the most is happening in our city.”

Beck said since the start of the year, domestic violence reporting is down 10 percent, while sexual assault reporting dropped 25 percent among Hispanics, compared with the prior year, which are bigger reductions than for any other demographic.

“Imagine someone being the victim of domestic violence and not calling the police,” he said. “Imagine your daughter, your sister, your mother, your friend not reporting sexual assault because they are afraid the family will be torn apart.”

Garcetti acknowledged that what is causing the decline in reporting “is a very difficult thing to quantify,” and it is tough to say if legal tactics such as ICE officers posing as police officers have contributed to the numbers.

“What we’re getting in terms of the statistics are worrying,” he said, adding that “we’ll do more digging in them, but there seems to be a trend already just in the first couple months, and we’re not going to turn the clock backward. We’re going to let people know they’re safe and that they should come and report crimes.”

The directive also aims to prevent city employees from cooperating with any federal civil immigration enforcement actions or use any city dollars or resources, unless they are legally required. Department general managers, directors and commissioners will also need to report to the mayor’s office and the LAPD chief any efforts by federal immigration officials to gain cooperation or use city resources to enforce “federal civil” immigration laws.

The city executive action also aims to protect individuals’ immigration information, requiring that data on someone that can be used to learn their immigration status be treated as confidential information under existing city policy.

All departments will also make copies of a “community resource guide for immigrant Angelenos” available at their offices or on their websites, as well as designate an “immigrant affairs liaison” to work with the mayor’s office.