For users of the online employment eligibility tool offered by the U.S. Citizenship and Immigration Services (USCIS) called E-Verify, the agency has released a new User Manual for Employers.
Some states mandate the use of E-Verify to qualify new hires to work in the United States, and federal contractors and subcontractors often must use the online database system as well (which is free). As part of the immigration reform measure currently going through Congress, a much broader, even nationwide E-Verify mandate is envisioned.
The manual, available for download by clicking on the link in the first paragraph, is Publication M-775, dated June 2013.