The Obama administration, while deporting a record number of immigrants convicted of crimes, is sparing one group of illegal immigrants from expulsion: students who came to the United States without papers when they were children.

In case after case where immigrant students were identified by federal agents as being in the country illegally, the students were released from detention and their deportations were suspended or canceled, lawyers and immigrant advocates said. Officials have even declined to deport students who openly declared their illegal status in public protests.

The students who have been allowed to remain are among more than 700,000 illegal immigrants who would be eligible for legal status under a bill before Congress specifically for high school graduates who came to the United States before they were 16. Department of Homeland Security officials said they had made no formal change of policy to permit those students to stay. But they said they had other, more pressing deportation priorities.

“In a world of limited resources, our time is better spent on someone who is here unlawfully and is committing crimes in the neighborhood,” John Morton, the head of Immigration and Customs Enforcement, said in an interview. “As opposed to someone who came to this country as a juvenile and spent the vast majority of their life here.”