Assisted Suicide

There is a stigma behind the elderly population in the sense that they aren't able to make rational and justifiable decisions in their life.  It is believed that through old age their body along with their mind begins to deteriorate.  I myself was guilty for developing this stereotype until I became a care aide and started working with the geriatric population.  I have witnessed first hand, how despite age one can still have dependable mental function.
At the facility I work for I have encountered such individuals, which have the majority of their mental capability.  For example there is an individual in his 90's who still does all his own taxes as well as another who completes the daily crossword in a matter of minutes.  They are able to understand, comprehend, and remember information and material that is presented to them.  Despite this many still blame the though of suicide in geriatrics to be from a declining mental state.  In cases of dementia and Alzheimer's this may be the cause, however their are seniors who wish to take their life with coherent mental function.  
There have been instances where client's starve themselves in order to pass away quicker than their body originally planned.  In one client's case she decided that she wanted to pass away so she remains bed ridden, eats little to nothing, and asked her doctor to given her sub q morphine three times a day.  Morphine is used to suppress pain as well as slowly stop the function of major organs.  Morphine has been used to quicken the dying process and allow for patients to pass with as little discomfort as possible.  This patient was previously a nurse herself and understood the implications of her actions and requests.
My belief is that if a geriatric patient wishes to pass than they should have the right to do so.  Rather than starving themselves, which could take a matter of months, or having injections of morphine there should be a quicker alternative to relieve pain and suffering.  Another issue that should be addressed is whether morphine should be used at the end of life.  If assisted suicide is illegal shouldn't morphine be considered as well since it increases mortality?