Dr Peter Saunders, from Care Not Killing, a UK based organisation which promotes care and opposes euthanasia said Paul Lamb is seeking a "very radical change in the law."
He said: "If he was successful in getting that legal change it would drive a coach and horses through not the suicide act but the murder act as well and that would put a lot of vulnerable, elderly people at risk
"The proper place to be making this decision is not in court, it's in Parliament", he added.
More top news
The Duke and Duchess of Cambridge arrived at the London Palladium Theatre an hour after scheduled.
A member of circus staff reportedly "neutralised" the big cat.
Warning in force for ice across many northwestern areas.