However ACT government officials say the arrangement won’t disadvantage claimants or lead to shopping between the two schemes.

Under the proposed CTP scheme, anyone injured in a motor vehicle accident will be able to access treatment, care and income support for up to five years regardless of fault.

The Barr government says it will mean an extra 600 people injured on Canberra’s roads per year will be able to access paid treatment and care, although the legal fraternity says it comes at the expense of lump sum payments for 90 per cent of claimants under the current scheme.

As it stands, workers injured in a car accident can file both a workers compensation and CTP claim, although one scheme pays back the other.

That will no longer be the case under the incoming CTP scheme, which has similar benefits to the workers compensation scheme.

Under Treasurer David Nicol told annual reports hearings recently the government was still working through how the schemes would interact, but it would likely involve a choice between schemes.

“I think the matter of question is how long is that person [going to] have an opportunity to choose a scheme, can you change your decision after a certain period of time, questions of that nature. So that’s where complexity arises and we’re just working through that now, going through different cases and what it means for different people and different situations,” Mr Nicol said.

“We’re looking at cases and seeing what typically happens in circumstances of injuries, what period is reasonable for people to choose and when are they able to make that choice depending on the seriousness of their injuries etcetera and I think obviously there’s a rationale to give people a very reasonable period to choose, they should be able to choose the circumstances that best suit their needs at the time.”

The guide to the exposure draft of the legislation said claimants would only have one month to pick, which Blumers Lawyers director Noor Blumer described as “a ridiculously short period of time”.

“Such a decision should not be made until there is a proper understanding of the extent of the effect of the injury on the person in terms of long term treatment and ability to work,” she said.

But Mr Nicol told the committee there was “a desire of course not to have people change between the schemes unnecessarily”.

“We don’t want to cut the decision making off too soon before the people have actually gone through the immediate medical assistance, immediate treatment etc so it's a judgement more about when that person is in the best possible place to make a fully informed decision so what their long term prognosis is, to be able to understand and to be advised of the benefits under both schemes etc as so they can make a rational decision. We do not want them to make a decision in haste they will subsequently regret,” he said.

The directorate's executive director of workplace safety and industrial relations, Michael Young, said there were differences in the benefits in both schemes, particularly in income support.

CTP claimants will be able to get 95 per cent of their income for three months then 80 per cent for five years, with only those classified as over the 10 per cent whole of person impairment threshold able to sue for longer support.

Workers compensation claimants can get income support based on their average weekly earnings until they return to work, or a top up if they’re performing different duties and earning less.

However, Mr Young said the difficulty in making a successful claim for a work-related car crash meant it was unlikely people would shop between the two schemes.

“For a common law damages settlement to succeed under the workers compensation scheme there needs to be negligence by the employer, it's very difficult to show negligence in the case of a journey claim where the injury you would expect is on a public road so we don’t see a lot of common law settlements in journey claims,” Mr Young said.

“Where we have seen them it tends be around shift work and fatigue where [employers] had some sort of control under so workers compensation common law around motor vehicle claims on journeys tend not to have a high frequency of common law settlements.”

Mr Young also said it was difficult to compare benefits as it depended on how long and how severe one’s injuries were as to which scheme was better.

“Hypothetically if an injured worker knew exactly how long they were going to be injured for and the amount of earnings they were going to lose, then it would be a relatively simple things to do a calculation and form a view on which services are best or would result in a particular financial outcome,” Mr Young said.

“It really does depend on the injury severity we’re talking about so there is no fixed one scheme is better than the other, the answer is it depends, which is why I believe the policy in place is to have a choice because that provides that, effectively ‘no one is worse off’ is the wrong definition to use because at the moment there is no choice to make, they'd be tied to the workers compensation statutory benefits and now there is a choice so in a sense there's a chance to improve the position of workers with dual coverage by allowing a choice between the two.”

However Unions ACT told a separate inquiry into the CTP bill that any sections of the legislation that would affect the rights of injured workers should be removed.

“Our understanding is that currently a person injured in a work-related motor accident can access the larger compensation benefit of the two schemes (either CTP or workers compensation),” its submission said.

“The proposed scheme appears to require that the injured worker choose between the two schemes at an early time, and then be excluded from the other scheme. We are also concerned that a person receiving workers compensation could be prevented from accessing compensation under the new CTP scheme.”

The draft legislation will be introduced into the Legislative Assembly next year.