Governments and medical authorities most often all conform to the one view that suicide is something that should be prevented under all circumstances, and thus you get what other users have described above as the loss of the right to control your own body in whatever way you like. Suicide is stigmatised in almost any official way - even the name paints it as something assumed wrong - to commit suicide; suicide victim.
I've always been an open supporter of the right to end one's own life, but at the same time what I think is most important is that a person is emotionally mature enough to handle such a concept and decision. How can we tell that? We can't, and sometimes we can't even if we are that person, so it creates a lot of grey areas regarding whether it seems right or wrong. I don't think personally there is a right or wrong when it comes to suicide.
To give a crude, simple example, to me it would seem absurd for a young person, who still has a lot to learn in life, to commit suicide on the eve of breaking up from a relationship, whether it was long or short. That's an example of someone making an unfortunate and rash decision without giving themselves time to think about anything properly. On the other hand, someone young or old, who has taken a lot of time and thought into making the decision, feels that either they are already satisfied by everything they've gone through in life or feels they have gone through so much that they'd rather not continue, makes the decision to end his/her life. This person makes sure to carefully tie up loose ends in relationships and let everyone important know how they should feel about this person. This is a person who is mature and should not be criticised for making the decision.
There are also things that trigger people to commit suicide. If someone has been depressed for a long time, has made efforts to move his/her world to make things better, but in the end suffers a huge emotional blow and decides enough is enough, how can we blame this person? Humans don't have the ridiculous optimism of Hollywood movies and teenage fiction. This is different to the relationship example I wrote before. Someone I knew was going through awful depression but making every effort to pull through it with her boyfriend and her very supportive friends. After becoming pregnant, she felt she could really make a new start and help herself, but then the miscarriage came. It was the last straw, and she sadly decided she couldn't go on anymore and start everything again. It's this sort of suicide that makes people feel the deepest sadness and regret - that despite everyone pulling together to help, the outcome still ends tragically. This is sad because it happened, but people should not feel they carry responsibility for not preventing it. Nothing of this was the fault of the person who died, or the people who tried to help.
But you know, suicide isn't always a product of misery. For someone who has tied up all loose ends in their life, decided on the action carefully, and really feels it is what they consciously want to do, do you think they feel miserable? Not everyone walks off that bridge with tears and total melancholy. Governments and medical authorities, for the reason of sticking to the 'prevailing morality' as such, could not accept that the decision to commit suicide could be a conscious, sensible or even positive decision to some. People don't realise that some people who decide to end their lives do so feeling relieved, philosophically satisfied with their decision, and having a genuine optimism about leaving the world. I know because I've known people like this. Doctors and psychiatrists either refuse to accept that a person could think that way, or that thinking in such a way is some form of delusion requiring treatment. And then people wonder why some people adamently refuse to find 'help'.
To sum up this post, I do not believe in a right or wrong when it comes to suicide. There is prepared and unprepared, emotionally mature and immature, foresight and impulse (impluse not necessarily being immature), and finally, optimism and acceptance, and melancholy depression as two ends of a wide spectrum.