In recent years, immigration attorneys say, concern about foreign gangs entering the U.S. has prompted Washington to delay or deny green cards that are crucial who want to apply for immigrants who want to file citizenship application form, to some applicants with tattoos. The tattoo checks have ensnared scores of immigrants—mostly from Latin America—even though they have no criminal conviction. The denials are based on a section of immigration law that justifies “inadmissibility” on national-security grounds, including possible affiliation with criminal organizations.