I think part of the problem with that particular situation is that it's very vague. "Allow euthanasia" doesn't say who can do what they can do to assist the person in ending their life, who can authorize it and how it's authorized, etc. You can bet your sweet booty that any real-world euthanasia law would spell these things out in minute detail in excruciatingly dense legalese - and any legitimate health care provider who intended to help patients end their lives would want it so, to cover their own arses!

My personal opinion on the matter is that the right to end one's own life is a fundamental part of controlling one's life, a fundamental liberty right. Therefore, assisting someone in ending their life is not inherently criminal. That said, the state and individuals have a strong interest in making sure that, in assisting someone in ending their life, the assistor is a) actually carrying out that person's wishes, and b) that person's wishes are well-informed, that is, that he or she understands as accruately as possible within the bounds of medical science the chance of surviving his or her illness or injury, or how long it will be before he or she dies "naturally," and how much more suffering he or she is likely to endure. Finally, the definition of "assisting" should contain the element that the individual ending his or her life must "pull the trigger," that is, make the ultimate decision or perform the final act that makes the end of his or her life irrevocable. A circumstance that doesn't include that final clause is something else, covered by living wills and the like, that should be legislated separately.