Four British doctors are attempting to take their professional body to the High Court over an assisted suicide survey they believe is illegal.

The doctors, two of whom are Catholic, say they believe the Royal College of Physicians has acted "unfairly and unlawfully" by setting a supermajority of 60 percent of votes to retain the college's existing opposition to assisted suicide.

The college has said it will adopt a policy of neutrality if the 60 percent threshold is not met.

But the four doctors said in a statement -- sent by email to Catholic News Service March 6 -- that the threshold would be impossible to meet because there were three questions in the survey instead of two.

The last survey on assisted suicide that was conducted by the college -- carried out in 2014 using two questions -- found that 58 percent of members opposed the practice.

The four doctors applied for a judicial review March 4 on the grounds of "irrationality" and a "breach of legitimate expectation" in the way the poll had been conducted.

One of the four, Dr. David Randall, a London-based renal medicine specialist, said, "The public has a right to know what doctors think about this important issue.

"Going neutral would silence the voice of the majority of doctors who oppose the legalization of assisted suicide," he said in a statement March 6.

"Neutrality would provide tacit support to a campaign to change the law, which fewer than a third of RCP members supported in the most recent poll on this issue," he added.

In a March 7 statement sent to CNS, the royal college said its governing council "opted for a supermajority so that the college's position better represents the range of views throughout the whole membership."

"Our council includes wide representation elected by the fellowship and from the 30 different areas of medicine our members cover," the statement said.

"Should the RCP adopt a neutral position, that does not signal 'tacit support' for a campaign to change the law," it added. "Rather it allows the college to reflect the fact that there are strongly differing views in medicine, just as there are in society."

Paul Conrathe of the London-based Sinclairslaw, the lawyer representing the doctors, said, "It is very concerning that the body representing physicians has acted in such a cavalier manner.

"It should have conducted a genuine consultation with its members and fellows. Instead, it has presented a fait accompli, and so my clients have no other option than to seek redress from the court," he said in a March 6 statement.

The other doctors involved in the legal challenge include Dr. Dermot Kearney, a cardiologist who serves as president of the Catholic Medical Association; Dr. Adrian Treloar, a geriatric psychiatrist and a Catholic; and Dr. Kathy Myers, a retired palliative medicine consultant.

Dr. Kearney has accused the royal college of "gerrymandering" and of organizing a "sham" survey so it could ditch its traditional opposition to euthanasia and assisted suicide. He was among more than 2,000 doctors to express grave concerns about the way the college was conducting the vote, which closed March 1.

The college also has come under pressure from other doctors to explain what it intends to do to address the problem of multiple voting.

One palliative care doctor, who does not wish to be named, told CNS March 4 that she knew of a colleague who had voted at least three times.

Another palliative care consultant, Baroness (Ilora) Finlay of Llandaff, told CNS March 3 that she had voted twice to test the system, and her multiple votes had not been detected, so she lodged a complaint.

She later received a reassurance from the college "that every effort is being made to ensure multiple responses from individuals are detected."