Although legislators rarely have easy decisions to make, I have found the vote on the Terminally Ill Adults (End of Life) Bill (often called the Assisted Dying Bill) one of the hardest to cast in nearly 20 years of being a Member of Parliament.

I think that Kim Leadbeater MP (the promoter of the bill) and those who have worked with her have made a sensible decision to limit the bill's scope to those who are terminally ill rather than extending it to others subject to 'intolerable suffering' or other categories of individual which are challenging to define but which are included in similar legislation elsewhere in the world.

I also think they have worked hard to include in the bill safeguards to protect those who may be vulnerable to abuse of its provisions.

If the bill were to become law, I would want those safeguards to be enhanced.

As currently drafted, the bill allows doctors to seek external expert assistance in certifying, as they must, that an individual seeking assistance to die is both terminally ill with six months or less to live and has the mental capacity to make that choice.

Doctors cannot however seek similar assistance on the difficult judgment of whether the individual concerned has been pressured or coerced into their decision. This of course is not just the question that probably concerns the most people about this prospective change in the law, but is also one of the most difficult questions for a doctor to answer.

It is not a medical judgment.

I appreciate that the bill also requires a court to consider this matter when assessing the doctors' judgments on all criteria, but I believe doctors operating in this complex area should not be required to make professional judgments they are ill-equipped to make.

I am also concerned that the maximum sentences for the new criminal offences created by the bill are inconsistent and in one case insufficient, but these are fixable problems. I do, however, have a much more fundamental concern with the bill.

I am most concerned about the signal we send with this legislation.

Signals sent by changes in the law matter. When Parliament changes the law, it provides for consequences for individuals who break the new law, but it also intends to change behaviour.

Creating new criminal offences, or increasing maximum sentences to further discourage something like drink driving, is an act we hope everyone will take notice of and act differently because they recognise that Parliament, on behalf of society as a whole, is signalling its disapproval of certain actions or practices.

That is an impact we hope and expect our legislation to have. So if that is true for legislation that makes unlawful what was previously lawful, why shouldn't the same be true for legislation that makes lawful something that was previously unlawful?

We are sending a signal there too – that society, through parliament, believes that something which we used to think was unacceptable is now acceptable. In this case, that assisting someone to die is now something of which we approve.

I believe that is bound to have an impact on those who, in great distress at the ends of their lives, may already be thinking that it would be better for all concerned if they were out of the way.

I do not want to live in a society where anyone, even the terminally ill, can believe that their lives are not valuable and valued to their last moments, and I fear that this bill, though it is not its intent, brings such a society closer.

I have spoken, including in recent days, to those who want this bill to pass for the best of reasons.

Their desperation and pain is what has made this vote hard to cast, and if we could legislate only for those who act for the best of motives, and eliminate in our drafting all risk of some taking a right to die to be a duty to die, then supporting this bill would be much easier, but we cannot.

However good our intentions and however thoughtful our drafting, I have concluded this will remain just too big a risk to take for some of the most vulnerable in our communities who require the greatest protection from the law.

That is why I cannot support this bill.