My BIL recently was assisted in his death here in Canada. He had been diagnosed with ALS and was in the final stages of the disease. Like Jane43 and cocoPops have stated, there is a procedure to grant the application, and needs to be approved by two different doctors.
From what my sister has told me (I was unable to travel to visit either before or after his death) it was very peaceful and the hospice care very compassionate. This was just in January, so there are certain things that I have not asked her, such as who decides at what stage of an illness to administer the dosage.
this is from the website:
That illness, disease or disability is in an advanced state of decline and irreversible with natural death being reasonably foreseeable.
This in itself will not allow someone to ask for assisted death upon a diagnosis of an illness. From what I can gather, it is a compassionate way to end life, and I hope one day I can be granted that dignity.