It is hard not to have sympathy for those who are advocating for the legalization of assisted suicide as a way of alleviating suffering. Suffering is a terrible reality of human life, an experience of evil that cannot be avoided. Without a Christian understanding of the meaning of suffering (see St. John Paul’s magnificent letter Salvifici Doloris), it is a fearsome thing to face.
But even a non-believer should be able to discern the clear danger signs about the inevitable effects of legalizing any form of suicide, and step away from that precipice
The experience of European countries that have legalized assisted suicide are test cases. We can see the way that the practice spread from the terminally ill, to those with chronic illnesses, to those with psychiatric or developmental problems, to minors, and utimately to people who were put to death even though they never requested it. It is abundantly clear that there are no limiting principles that can stop the spread of assisted suicide, and its progress to outright euthanasia
The danger signs can also be seen in the most recent statistics released by the Centers for Disease Control on the incidence of suicide in the United States. 
The situation is truly alarming — suicide has increased dramatically over the last two decades. Here are some of the lowlights of the report: 

  • From 1999 through 2014, the suicide rate increased 24%, with the pace of increase accellerating after 2006.
  • Suicide rates increased from 1999 through 2014 for both males and females and for all ages 10–74.
  • In 2014, the rate for males was more than three times that for females, but the percent increase was greater for females (45% increase) than males (16% increase).
  • Although there were few suicides compared with other age groups, the suicide rate for females aged 10–14 tripled.
  • In both 1999 and 2014, suicide rates were highest among men aged 75 and over. Men aged 45–64 had the second-highest suicide rate for males in 2014 and the largest percent increase (43%) in rates.
  • Suicide is increasing against the backdrop of generally declining mortality, and is currently one of the 10 leading causes of death overall and within each age group 10–64.

With this information, how can it possibly make sense to legalize assisted suicide, which sends a clear, strong message that some lives are not worth living, and that death is the solution? Shouldn’t we instead redouble our efforts to convince people to reject suicide?
Advocates for assisted suicide insist that society defer absolutely to their autonomy, based on a notion that people have absolute liberty to do whatever they like. Yet our society has never done so. As Justice Oliver Wendell Holmes said in his famous dissent in the Lochner case, "The liberty of the citizen to do as he likes so long as he does not interfere with the liberty of others to do the same, which has been a shibboleth for some well known writers, is interfered with by school laws, by the Post Office, by every state or municipal institution which takes his money for purposes thought desirable, whether he likes it or not." The idea that people have complete autonomy is both incoherent and an invitation to anarchy
Again, the suffering of individuals is compelling and naturally rouses sympathy. We must do everything we can to alleviate the physical, psychological, social, emotional and spiritual suffering of all our brethren
But the particular desires of individuals cannot be the basis of making law for our entire society. St. Thomas Aquinas defined law as "an ordinance of reason for the common good". The good of all of society must be the controlling concern when we make law, not the idiosyncratic interests of some people or groups.
The danger signs of relaxing our immemorial ban on suicide are very, very clear that it would lead to many more unnecessary and tragic deaths. We must continue to resist any effort to legalize any form of suicide, for the good of all of society.