Juan Rivas, who has held a green card and worked as a day laborer in Los Angeles for more than 20 years, was detained by federal immigration agents at a Home Depot parking lot on the Fourth of July. Rivas said agents began hitting him and threw him to the floor as he tried to show his legal documents. He is one of eight Americans and one green card holder who have filed joint civil rights claims against the federal government alleging wrongful detention, racial profiling and excessive force.