Washington Mayor Muriel Bowser (D). (Andrew Harnik/AP)

Mayor Muriel E. Bowser (D) quietly approved legislation making the District the seventh jurisdiction to allow terminally ill patients to legally end their lives, but it is unclear if Congress will intervene in an issue that has been debated in statehouses across the country.

The mayor signed the legislation Monday, clearing it to be sent to Capitol Hill for a 30-day review period. Some local opponents of the law have vowed to press the GOP-controlled Congress to use its rarely invoked power to void District laws.

The earliest the law would take effect would be next October.

The legislation, sponsored by Council member Mary Cheh (D-Ward 3) is modeled after the nation’s first physician-assisted suicide law, enacted in Oregon. It will allow doctors to prescribe fatal medication to patients with less than six months to live. Patients must make two requests over a period of two weeks and ingest the drugs themselves.

Bowser has not publicly commented on the legislation, and refused through a spokesman to explain why she signed it. It was one of the most emotionally charged issues of the year in D.C., drawing hundreds of supporters and opponents to Council chambers and bringing some lawmakers to tears as they shared personal stories that influenced their votes.

Bowser’s health director LaQuandra Nesbitt raised issues with the legislation when testifying before Council last year, including that some medical professional groups saw assisted suicide as violating the Hippocratic Oath to do no harm.

In an interview Tuesday, Nesbitt said Council had addressed many of her concerns with amendments from the mayor’s office making clear that people could not kill themselves in public places, such as the National Mall, and providing for a process for health officials to document and investigate deaths under the law if necessary.

D.C. Del. Eleanor Holmes Norton (D) has vowed to protect the law from any Congressional interference. No member of Congress has publicly opposed the legislation yet, and a spokeswoman for Rep. Jason Chaffetz (R-Utah), whose chairs the committee with jurisdiction over District laws, said the lawmaker had not comment.

Congressional attempts to try to override Oregon’s law after it was enacted in 1998 failed. Since then, voters approved similar laws in Washington state and Colorado this November, as well as the legislatures of Vermont and California. The practice is considered legal in Montana because of a court ruling.

Aid-in-dying advocates praised Bowser for signing the legislation. They say success in D.C., following passage in California last year, shows their movement can win in diverse jurisdictions after early victories in overwhelmingly white states.

National polls have shown African Americans are the most likely to oppose legislation allowing terminally ill people to end their lives, and they make up nearly half of the District’s population.

“Every terminally ill adult should have the freedom and liberty to make their own decisions about how they want to die in comfort and peace, in consultation with their family, physicians and spiritual leaders,” said Donna Smith, an organizer with the national right-to-die advocacy group Compassion and Choices.