The British House of Commons narrowly approved an “assisted dying” bill on Friday, as critics warned the legislation contains weakened safeguards that could endanger vulnerable patients.

Catholic priest John Howard, who led people in prayer outside parliament, called the bill’s passage “a dark day for our country.”

The legislation, which passed with a narrow 314-291 vote, would allow mentally competent, terminally ill adults in England and Wales with six months or less to live to choose to end their lives with medical assistance.

Critics note that support for the bill has weakened since November’s initial vote of 330-275, as some lawmakers withdrew support after safeguards were diluted.

The original plan requiring court approval for assisted deaths has been replaced with a requirement for review by a panel including a social worker, senior legal figure, and psychiatrist.

British Health Secretary Wes Streeting warned that the bill in its current form could lead to a “chilling” scenario in which the cash-strapped National Health Service (NHS) could pressure terminally ill patients into an early death to save NHS money.

Care Not Killing released a statement calling the bill “deeply flawed and dangerous,” and CEO Gordon Macdonald slammed the process, criticizing the fact that “[m]embers of Parliament had under 10 hours to consider over 130 amendments to the Bill, or less than 5 minutes per change.”

“Does anyone think this is enough time to consider changes to a draft law that quite literally is a matter of life and death?” Macdonald continued.

Prime Minister Keir Starmer voted in favor of the bill, which now proceeds to Britain’s upper chamber, the House of Lords, for months of further scrutiny.

The unelected Lords are traditionally reluctant to block legislation passed by elected members of the House of Commons. However, insiders told the Times this bill has many critics in the House of Lords, and could lead the upper chamber to break this norm.

One source told The Times there were “plenty of black arts that could be used to kill the bill off,” and that they could “not imagine how it could get through.”

Another peer concurred: “This bill is still going to have an extremely difficult path to the statute book. There are enough peers in the Lords who are vehemently opposed to it becoming law and more than enough opportunity for them to thwart it. It is far from a foregone conclusion.”

However, many in the U.K. celebrated the bill’s passage despite flaws pointed out by critics.

Emma Bray, a 42-year-old mother of two with motor neuron disease who has been given six months to live, celebrated the vote result.

“This result will mean that people will not have to go through the same suffering I have faced,” Bray told Reuters, revealing she had been planning to starve herself to death next month to relieve her pain.