It was a busy week for San Francisco courts as the U.S. District Court blocked a U.S. plan to begin cracking down on employers who use undocumented workers. The Social Security Administration is preparing to send letters to employers who have employees with names that do not match Social Security numbers and the Department of Homeland Security Department would then fine companies that ignored the warning letters. The ACLU and AFL-CIO brought the lawsuit arguing that Social Security database is full of errors and that the letters could lead to employers discriminating against some employees.