Undocumented immigrants in committed same-sex relationships may have a better chance of avoiding deportation under a new Obama administration policy.

Officials will take into account same-sex relationships when considering whether to pursue deportation cases against undocumented immigrants, Department of Homeland Security Secretary Janet Napolitano said this week. She affirmed the shift in a letter to lawmakers who had asked for more information about a new initiative, unveiled last summer, that directs immigration agents to take certain factors into account when deciding who is deportable.

The new policy relies on the concept of "prosecutorial discretion," under which Immigration and Customs Enforcement agents and federal prosecutors have leeway in deciding whether or not to take up deportation cases. Casting the move as a way to prioritize limited enforcement resources, the Obama administration instructed agents to emphasize immigrants with criminal backgrounds and to show leniency to immigrants who had served in the military, obtained an education or cultivated deep family ties.

It was unclear whether same-sex relationships could be used to help establish that undocumented immigrants had built families in the United States. Napolitano's letter confirms that they do.

"In an effort to make clear the definition of the phrase 'family relationships,' I have directed [Immigration and Customs Enforcement] to disseminate written guidance to the field that the interpretation of the phrase 'family relationships' includes long-term, same-sex partners," Napolitan wrote, adding that the weight given to those same-sex relationships would vary from case to case.

Same-sex couples still face higher hurdles when it comes to securing immigration benefits. The Defense of Marriage Act prohibits the federal government from recognizing same-sex marriages, which means that American citizens still cannot sponsor same-sex spouses for legal permanent residency.

But Napolitano's clarification still represents a victory for gay rights advocates who had been closely watching the new prosecutorial discretion policy.

“Throughout the LGBT immigration community today there is much relief and much hope that this signals a turning point," said Steve Ralls, communications director for the organization Immigration Equality, which advocates for gay immigrants. "It’s an amazing development that the admin is putting in writing their clear intent that families not be separated."

Ralls said that the shift is significant because it codifies how immigration agents across the country will carry out the new prosecutorial discretion guidelines. Immigration advocates have worried that implementation of the new policy could vary widely in individual field offices.

"The administration had verbally assured us in the past that they would work to prevent U.S. citizens from being separated from their partners, and today they put that assurance in writing," Ralls said. "The guidance is especially important because it is going to be in writing, which means that field officers all across the country who are reviewing deportation cases will know and understand that family ties for gay and lesbian couples will be included."