Just as the voting forms in the federal government's postal plebiscite on same-sex marriage are mailed out to homes this week, a voluntary euthanasia bill is also coming before the NSW parliament.

The issues share many similarities but also stark differences that must be negotiated by the politicians.

The first difference is that the assisted dying bill is to be debated in parliament – where it should be – rather than being outsourced to a non-binding survey as has been the case with same-sex marriage.

The second difference is that it is hard to see how anyone's life could be changed by the legalisation of same-sex marriage – unless, of course, they want it to be.

The legalisation of same-sex marriage should bring only joy to those in the community who wish to take part in it and, despite what opponents say, will have negligible impact on those who do not.

Then there are the similarities.

Most obvious is that both issues deal with the question of personal rights – either the right to marry who you want and the right to die when you are ready.

Both should be fundamental rights in a free, progressive society and those rights should properly be legislated by our parliaments.

But we should feel some sympathy for the MPs as they consider the assisted dying bill from Thursday.

Even if one supports the idea that a suffering person should have the right to choose to die, it is a far different thing to be charged with writing the legislation that allows that to happen.

We've read and heard of many clear cases where clear-minded people have pleaded for the right to end their own suffering and no-one could not be moved by those cases.

But at the back of the minds of MPs will be those vulnerable, particularly elderly, citizens who may feel undue pressure to make a decision they are not yet ready to make.

These are the people who must be protected by our laws, not exposed by them.

So while the assisted dying bill makes its passage through parliament, we should not be too critical of politicians who seek to take the time to get it right.

Our MPs have let us down on same-sex marriage. Let's hope they get it right on assisted dying.