U.K. Members of Parliament will hold a landmark vote on assisted dying on Friday as they decide whether to allow terminally ill people with less than six months to live to opt to end their own lives.

Under the legislation put forward by Kim Leadbeater, a backbench member of the governing Labour Party, assisted dying would be restricted to adults with a terminal illness who are expected to die within six months. Two doctors and a high court judge would also be required to approve the decision. It broadly follows the model from the U.S. state of Oregon, meaning that lethal drugs must be self-administered.

It will be the first vote on the issue since 2015, though if the bill passes its so-called second reading, there are still several more parliamentary steps before it becomes law, including opportunities to amend it. If the legislation is successful, it would be a fundamental social reform bringing England and Wales in line with about a dozen countries that permit assisted dying such as Canada and Switzerland, as well as 11 U.S. states.