A memo signed in April by President Obama that bans hospitals from discriminating against gay men and lesbians went into effect on Tuesday.

The order prohibits hospitals that accept federal funding from Medicare and Medicaid, the government's elderly and poor health care programs, from discriminating on the basis of a variety of characteristics, including sexual orientation and gender identity. It also prevents hospitals from denying visitation rights to the partners of gay men and lesbians, and requires officials to honor patients' wishes of who can make medical decisions on their behalf.

Gay rights groups have called the new rules a small but significant contribution towards equality in the absence of the legal right to marry in most jurisdictions.

“The president's directive is a small, but welcome step forward,” Evan Wolfson, executive director of Freedom to Marry, said in a statement. “It addresses one of the many ways same-sex couples and their loved ones are made vulnerable and harmed by the denial of marriage and the safety-net of protections marriage brings – in this case, the assurance that a spouse can be by a loved one's hospital bedside and participate in medical decision-making at a time of great need.”

“Without marriage equality, this memo is absolutely critical for ensuring that the federal government is protecting the medical rights of all families and not discriminating against certain classes of citizens,” New York Representative Jerrold Nadler said in a statement.

“LGBT families need and deserve the same civil rights as other American families, and I applaud this progress in that long struggle,” he added.