Comprehensive immigration reform is a frequent topic of presidential primary debates and is expected to take much of lawmakers' attention in Congress again this year. But until an overhaul takes place, employers must continue to ensure workers are documented properly, follow varying states' laws and avoid discriminating against workers on the basis of their nationality or citizenship status.

An estimated 12 million undocumented immigrants currently live in the United States. And the reality is that some might be working in restaurants under false identities and others are given jobs with no papers at all.

Whether a restaurant company handles verification and documentation itself or hires a law firm or human resources outsourcing company to do it, here are four things you need to know now about immigration laws.

The I-9 form verifies that an employee is eligible to work in the United States. The U.S. Citizen and Immigration Services division of the Department of Homeland Security updated the form last year to streamline the process. It shortened the list of acceptable documents that establish both a person's identity and eligibility to work in the United States, removing five documents and adding a new one. The agency said the removed documents didn't have features that help deter counterfeiting, tampering and fraud.

Download the new I-9 form and “Handbook for Employers, Instructions for Completing the Form I-9” from www.uscis.gov. Forms and immigration-regulation updates are also available from the National Restaurant Association at www.restaurant.org/immigration.

Employers must use the new form, dated June 5, 2007, as of Dec. 26, 2007, or face fines from the Department of Homeland Security. Companies don't need to fill out new forms for current workers, unless their work authorization is about to expire.

What hasn't changed is the need to check worker documents carefully, looking for misspelled words and grammar mistakes. Track the expiration dates of all employees' documents, regularly audit the forms and match employees with social security numbers, and check the employment history on each new hire. To avoid charges of discrimination, be consistent in these efforts with all employees, not just immigrants or those of a particular national origin.

To help employers comply with federal immigration laws, U.S. Citizen and Immigration Services launched the Basic Pilot Program in 1997. Last year, it was renamed E-Verify, and would have been made mandatory if Congress would have passed the immigration bill that failed last June.

The program enables employers to electronically check a person's eligibility to work by inputting a social security number and other document numbers into the system, which verifies the employee's status against online databases from the Social Security Administration and the Department of Homeland Security. The program is voluntary and free to use. For information, visit www.dhs.gov/e-verify.

Those who participate must check on all new employees within three days of hiring. They are not supposed to check current workers or those who haven't been hired yet. If new workers turn out to be ineligible, the employer has to fire them, but they don't have to report them to immigration enforcement.

Some companies, including Dunkin' Brands, appreciate the ease of use and the extra check, though use of the system does not provide “safe harbor” from enforcement efforts. Others say the databases have mistakes and are not updated quickly enough, which might lead to properly documented workers being fired. Opponents, including the Society for Human Resource Management, argue that the system is unreliable and doesn't fix the greater immigration problem.

SHRM is part of a group called the HR Initiative for a Legal Workforce, whose mission is “to improve the current process of employment verification by creating a secure, efficient and reliable system that will help prevent unauthorized employment.” The group proposes a private system that would incorporate fingerprints, retinal scans or other “biometric identifiers.”

States have taken it upon themselves to tackle immigration because the national legislature hasn't gotten anywhere. This makes following the rules confusing for companies operating in more than one state.

The National Conference of State Legislatures in fall found that there were 1,562 immigration-related bills introduced in statehouses in 2007. Of those, 244 were signed into law. The category with the greatest number of bills dealt with identification or driver's licenses; the second was employment-related issues; and the third was law enforcement.

For example, in Arizona, new regulations say that employers will lose their business license if they are caught hiring workers without proper documentation. In Illinois, a new law currently delayed in state courts would bar companies from using the E-Verify system.

The National Conference of State Legislatures maintains a list of states and their immigration legislation at www.ncsl.org.

The Department of Homeland Security is preparing to revamp its rules for employers who receive no-match letters, which inform them that a social security number does not match up with the employee.

In August, letters began telling employers that they needed to respond within 90 days to explain why the employee and number didn't match. In October, a federal court stopped those letters from going out, noting there are “serious questions” about the rules. Rather than fight the courts this time, the Department of Homeland Security will rework the regulations. The court's next hearing on the rules is scheduled for March 24, so expect to see the rules issued for public comment before that.