Paperwork that leads to death; PROFILE.
Before agreeing to assist a suicide, staff must determine whether the patient's desire to die falls within legal boundaries.
Clients, who can pay up to pounds 5,500 for assistance with their deaths, sign legally binding papers to stop relatives preventing it.
The law requires that a doctor sees those who wish to die at least twice before going to the "death room".
Patients have to end their own life - either with lethal doses of drugs or by turning off life support.
Each suicide is filmed so the clinic cannot be accused of killing people.
Staff work as volunteers to ensure there can be no conflict of interest.
Dignitas was founded in 1998 by Swiss lawyer Ludwig Minelli.
The organisation has helped 900 people commit suicide in a number of flats it owns in Zurich.
It has never been far away from controversy.
Former worker Soraya Wernli accused it of "dumping human ashes in Lake Zurich".
And sources also claim it uses a flat near a brothel for some of the suicides.
Dignitas denies it is running a "conveyor belt" operation.