The United States Department of Labor issued a groundbreaking rule change last week, granting couples in legal, same-sex marriages the same rights as those in opposite-sex marriages under the Family Medical Leave Act (FMLA).

The FMLA, which was enacted in 1993, allows eligible employees to take unpaid, job-protected leave for specified family and medical reasons, such as caring for a spouse suffering from a serious medical condition, with the continuation of the employee’s group health insurance coverage under the same terms and conditions as if the employee had not taken leave.

Under the new rule, announced earlier this week, the definition of “spouse” will be amended, so that an eligible employee in a legal same-sex marriage will be able to take FMLA leave for his or her spouse, regardless of the state in which the employee resides. The rule change was designed to conform the FMLA to the U.S. Supreme Court ruling in United States v. Windsor, in which the court struck down the federal Defense of Marriage Act provision, which had limited the definitions of “marriage” and “spouse” to opposite-sex marriages for purposes of federal law. Now, instead of looking at the state where the employee resides, the definition of “spouse” now depends on whether the employee entered into a legal marriage (including common law marriages) in any state or foreign country (if such marriage would be recognized as legal in any state). Thirty-seven states and the District of Columbia extend the right to marry to both same-sex and opposite-sex couples (Alabama, Alaska, Arizona, California, Colorado, Connecticut, Delaware, Florida, Hawaii, Idaho, Illinois, Iowa, Indiana, Kansas, Maine, Maryland, Massachusetts, Minnesota, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Vermont, Virginia, Utah, Washington, West Virginia, Wisconsin and Wyoming). Additionally, 18 countries extend the right to marry to both same-sex and opposite-sex couples (Argentina, Belgium, Brazil, Canada, Denmark, England/Wales/Scotland, Finland, France, Iceland, Luxembourg, The Netherlands, New Zealand, Norway, Portugal, Spain, South Africa, Sweden, and Uruguay).

The rule change, which will take effect on March 27, 2015, represents an important extension of same-sex couples’ rights under federal law. In announcing the rule change, U.S. Secretary of Labor Thomas E. Perez explained, “With our action today, we extend that promise so that no matter who you love, you will receive the same rights and protections as everyone else … All eligible employees in legal same-sex marriages, regardless of where they live, can now deal with a serious medical and family situation like all families — without the threat of job loss.” This change is substantial for employers because spousal leave now applies in many states that currently do not recognize same-sex marriages. For example, if a Michigan employer has an employee who was legally married to a same-sex spouse in California, then the employee would be eligible for spousal leave under the FMLA in Michigan, even though Michigan currently does not recognize same-sex marriage.

What should employers do now? To begin with, managers and FMLA coordinators should understand how this new final rule impacts FMLA for same-sex or common-law spouses. In many cases, policies will need to be changed to reflect that leave for legal same-sex spouses is covered under the FMLA. FMLA still does not apply to civil unions or domestic partnerships. Employers also continue to be permitted to require employees who take leave to care for a family member to provide reasonable documentation of the family relationship. Reasonable documentation may take the form of either a simple statement from the employee or documentation such as a birth certificate or court document. Employers may not use a request for confirmation of a family relationship in a manner that interferes with an employee’s exercise of FMLA rights, but it is permissible to request proof of marriage if proof had not been previously provided to the employer for some other purpose, such as obtaining health care benefits for the employee’s spouse. Employers should make such requests in a non-discriminatory manner.