Legislation based on the findings of the Royal Commission into Institutional Responses to Child Sexual Abuse are due to be debated when the ACT Legislative Assembly recommences sitting next week.

The draft laws, introduced into the Assembly in November, create a new offence for engaging in a "sexual relationship" with a child, based on prosecutors specifying an overall period of the "relationship" and two cases of abuse within that period.

The bill also makes "grooming" a child a crime and ensures an accused person's "good character" cannot be used to reduce their sentence, if that reputation was why they had contact with children in the first place.

But ACT Bar Association president Ken Archer warned some elements of the bill go too far.

Mr Archer said the grooming offence could outlaw some "benign" contact, such as showing students a video of sexual activity in sex education classes.

"The ACT Bar Association supports changes to the Crimes Act that will provide appropriate protections to children," Mr Archer said in a statement.

"However, the amendments to the Crimes Act that the government has proposed will mean that parents, other children and teachers will be liable to be prosecuted in relation to quite innocent conduct which should not attract a jail sentence.

"Sex education classes, the provision of contraception to young people and sexual acts between young people in a previously lawful and consensual sexual relationship will now be criminalised and will attract prison sentences.

"The offences set out in the bill are alarming and cannot possibly be enacted in the form in which they have been presented."

Mr Archer said the grooming offence needed to be linked to an intent to groom for a sexual purpose.

He also said the laws should not be backdated as it was unacceptable to change the basis of criminal liability retrospectively.

"Members of the Assembly must tread carefully in this area. It is simply unfair to criminalise behaviour that is intended to be protective of children," Mr Archer said.

"To send people to prison for behaviour that at the time it was undertaken was legal, cannot be what the government intends."

Mr Archer warned the courts would be asked to declare the laws incompatible with the Human Rights Act if the bill passed as is.

Last year, the ACT Bar Association warned the bill could risk an accused person's right to a fair trial, by not requiring particularised details for offences committed.

A spokeswoman for Attorney-General Gordon Ramsay said issues the Bar Association raised are "extremely technical, detailed issues relating to the drafting of the first two amendments".

"The legislation has never been drafted with the intent to criminalise actions that were previously completely legal, nor to criminalise any legitimate activity like sex education," she said.

"The Attorney-General met with the Bar Association this week and will continue to work with them to ensure that the provisions as drafted leave no doubt as to their intent, which is to ensure that crimes against children can be effectively prosecuted and that our children are safe."