Unless something changes significantly, at some point in the next couple of years it will become legal for doctors to help terminally ill West Australians end their lives.

It will be about a year until the McGowan Government's proposal to legalise voluntary assisted dying comes to a vote, but the odds appear to be in favour of those who want that to proceed — a fact both supporters and opponents within Parliament acknowledged this week.

Predicting how the vote in Parliament will go is made trickier by the fact that nearly every party offers its MPs a conscience vote on the matter.

But journalists and politicians alike have been counting the numbers this week, and all have reached the same probable outcome.

"If a vote was held today, we would not have much of a chance," one staunch opponent of voluntary assisted dying told the ABC this week.

A recent parliamentary committee said the law would limit "unnecessary suffering at end of life". ( Pixabay: sabinevanerp )

Both supporters and critics see the proposal as very likely to cruise through the Legislative Assembly, a chamber dominated by Labor MPs — despite the fact there are a number of euthanasia opponents within government ranks.

It is the Upper House where things would get more interesting, but a majority of Legislative Council MPs the ABC spoke to said they expected they would vote in favour of the bill.

The same outcome was reached by other media, along with the curious MPs gauging the level of support among their colleagues.

Brace for a fierce fight

But just because that outcome seems probable, it is important to note it is still far from certain.

One thing that is certain is a fierce fight on the matter.

Just take a look at Victoria, the only other state to pass laws like those which the WA Government will draft over the next year or so.

That measure became law in Victoria only after days of late night sittings of Parliament, highlighted best by a marathon 25-hour session of that state's Lower House, as MPs quibbled even over suggestions they break to allow parliamentary staff to get some sleep.

The public can expect fierce campaigning from both sides in the lead-up to the parliamentary vote. ( ABC News: Eliza Laschon )

It saw Victoria's politicians accuse each other of "appalling behaviour", and argue at length over points such as whether the word "poison" should replace the term "voluntary assisted dying substance" throughout the bill.

All that was before a vote which passed Victoria's Lower House relatively comfortably, giving WA a fairly clear indication of what could be on the cards for our own debate.

In the West, both sides of the divide are well-armed for the task — they have known this was coming for a long time now and have put large amounts of work into preparing their best cases.

Expect to see a significant amount of lobbying of MPs, advertising and public rallies, as both sides attempt to sway on-the-fence politicians.

Former premier Colin Barnett pointed to the parliamentary process which decriminalised abortion in WA 20 years ago as a sign of what could come.

"That did get nasty and this could get nasty too," he told ABC Radio Perth.

"When the bill gets into Parliament, it will be back to square one and the real debate will be at that point."



Undecided MPs weigh up options

The battle for public sentiment could be significant, with a handful of undecided MPs saying they will listen closely to their electorates in weighing up their vote.

The Government has booked three extra sitting weeks of parliament next year. ( ABC News: Jacob Kagi )

Also potentially significant will be the final model the McGowan Government's expert panel recommends, with plenty of MPs putting a caveat on their positions that their final votes would depend on how a legalised assisted dying system would actually work.

The fact that the Government has booked three extra sitting weeks of Parliament next year, directly related to the assisted dying bill, is a clear indicator of how protracted the debate could be.

A count of the numbers still makes it look likely that Parliament will vote to legalise voluntary assisted dying for terminally ill West Australians.

But what's even more likely is that, before we get an outcome, voters can expect a fierce public debate, intense lobbying and some late nights for MPs and staffers at State Parliament.