The government is hoping to pass laws on Thursday afternoon which would make directors of construction companies personally liable for financial penalties and orders to fix building defects.

But the Master Builders Association of the ACT has implored the government to defer debate on the bill, after receiving independent legal advice on Wednesday which it said had cast a cloud over the legislation.

The association's chief executive, Michael Hopkins, would not release the advice, but said it raised doubts about whether the laws were intended to apply retrospectively.

Mr Hopkins said the advice also recommended changes to the section of the bill which meant company directors could be served with orders to fix defects, even if they took up the role after the construction work was completed.

"We have called for the bill to be deferred today so that amendments can be made to address the legal uncertainty created by the bill," Mr Hopkins said.

The Housing Industry Association and ACT Law Society raised similar concerns in their submissions to an Assembly inquiry into the bill.

In its submission, the HIA said some of the measures would target construction work completed before the laws were introduced.

"Such laws are likely to be inconsistent with the general legal principle that a person cannot be expected to comply with a law that was incapable of being known and therefore unable to be complied with," the submission stated.

"It is simply unfair (and bad policy) to expect businesses to suffer consequences which were not known at the time of carrying out construction services."

The government argued in its submission to the inquiry that there were no retrospective provisions in the bill.

More to come