SAN FRANCISCO — Immigrant children living in the United States without legal status have been blocked from registering for school and accessing the educational services they need, according to a report on school districts in four states by Georgetown University Law Center researchers.

Such students have faced long enrollment delays and have been turned away from classrooms as the result of some districts’ arbitrary interpretations of residency rules and state laws, the researchers said.

All children living in the United States must attend school through at least the 8th grade or until they turn 16 under compulsory education laws in all 50 states. Many states allow students to enroll beyond that age, according to the Education Commission of the States.

But some districts’ elaborate paperwork requirements effectively have kept immigrant youths out of school, while lack of translation and interpretation services have left their families uninformed about the process, the report found.

The Obama administration’s efforts to find and deport the tens of thousands of unaccompanied Central American children and families who arrived during the 2014 surge of illegal crossings have further complicated the situation, prompting some students to avoid school for fear that they will be picked up by authorities, the report’s authors said.

“U.S. law is clear on this point – no child in the United States should be excluded from public education,” said Mikaela Harris, a Georgetown law student who co-wrote the study issued by the university’s Human Rights Institute and the nonprofit Women’s Refugee Commission. “That doesn’t always play out in practice.”

The report, which studied school districts in Florida, New York, Texas and North Carolina, calls for strengthening federal outreach to districts unaccustomed to serving newcomer populations and better assurances that educational access continues amid immigration enforcement.