Businessman Simon Binner travelled to Switzerland a year after being diagnosed with motor neurone disease.
He ended his own life by taking a lethal overdose of drugs with his wife at his side.
The emotional programme showed wife Debbie in tears at several points.
Peter Saunders, Chief Executive of the Christian Medical Fellowship, and a member of the Care not Killing movement told Premier's News Hour the BBC had broken several guidelines in the programme.
"They [the guidelines] say don't give information about the means used - well we saw that pictorially illustrated and described even down to the dose of the drug used.
"It says don't do things which normalise or romanticise or even sensationalise a suicide."
He added: "The BBC was clearly in breach of all of this, and they do have form in this area, I think this is the sixth documentary that we've had in the last eight years which has really been pushing the whole idea."
The Samaritans urges journalists not to show details of suicide methods because it could "prompt vulnerable individuals to imitate suicidal behaviour."
The charity's guidelines also encourage reports to avoid over-simplification of suicide.
A spokesman for the BBC said: "This is a sensitive observational documentary following one family's experience of assisted death, which explores some of the complex questions at the heart of this deeply divisive issue.
"The film does not serve to support either argument or intend to wholly represent the debate."