Leading medical and legal groups have called on government MPs to abandon a proposed law that would for the first time define a 20-week-old foetus as a "person".
The NSW Bar Association and the Australian Medical Association NSW have written to Liberal Party ministers to say the law is unnecessary and may impact on women's access to late-term abortion.
Liberal MP Chris Spence has put up a private member's bill called "Zoe's Law" - initially proposed by MP Fred Nile - which holds people criminally liable for the death of a foetus. It is named for central coast woman Brodie Donegan's unborn child, whom she lost at eight months when she was hit by a car.
The NSW Bar Association told Mr Spence the law's definition of the foetus as a ''person'' at above 20 weeks or 400 grams was "arbitrary'' and set a risky principle.
"When can a medical procedure designed in the interests of the mother be permitted to harm, let alone result in the destruction of, another 'person'?" the bar wrote. "Equally, can a mother consent to the destruction of the foetus where what is occurring involves the destruction of another 'person'?"
On Tuesday the AMA wrote to Health Minister Jillian Skinner because it feared the laws could have unintended impacts on doctors in areas from genetics to obstetrics. The current legislation, covering harm to the foetus as grievous bodily harm to the mother, was sufficient, a spokesman said.
"Any further extension … would have unintended consequences and flow-on effects in other areas of medicine," he said.
Women's Electoral Lobby Australia chairwoman Melanie Fernandez said a coalition of women's rights groups has repeatedly requested to be allowed to brief the Liberal Party, but this had not happened. "It would be really concerning,'' she said, ''if this bill were to go to debate without consultation with experts in the community.
She said that after initially saying the bill would go ahead on Thursday, Mr Spence had agreed to delay it again. Fairfax Media was unable to reach his office for comment.
Mr Spence previously said the law was never intended to infringe on abortion, which is illegal in NSW but is protected under case law as being acceptable if a woman is facing "serious danger to her life or physical or mental health".
A spokesman for Premier Barry O'Farrell said: "Liberal Party MPs will be given a conscience vote … for that reason it would not be appropriate for the Premier's office to organise such a briefing."