Prosecutors will no longer need to prove intent of further offending in order to charge someone with drink spiking, although they will need to show there was an intent to harm.

That means people who put extra alcohol in their friend's drink are unlikely to be risking jail time or a $75,000 fine.

However Attorney-General Gordon Ramsay said it could mean giving someone a stronger mixed drink than they asked for on a first date could be a criminal act.

"If reasonable person would have objected if they had known about the extra alcohol, that's a situation that will be covered by this law," Mr Ramsay said

People who accidentally spike a drink will not be criminally responsible.

The bill also provides a specific defence for medical practitioners who have to administer intoxicating substances as part of their job.

The law was changed because of a case that came before the ACT courts last year.

Sydney man Juswan Mokmargana, 46, spiked a woman's drink with two tablets of Stilnox while she was away from the table at a Canberra pub in April 2016.

Condoms, Viagra and sleeping drugs were later found in the man's suitcase, and prosecutors argued the drink spiking was part of a plan to rape the woman. But a jury found him not guilty of attempted rape.

After the trial Mokmargana admitted putting the drugs in the woman's drink - a crime under medicines and poisons laws that carries a one year maximum penalty - and he was handed a suspended sentence of six months jail for the crime.

In sentencing the man, the judge found the purpose of administering the drug was to render the woman into an at least drowsy state and to take advantage of her.

"This bill will provide fewer opportunities for technical arguments," Mr Ramsay said.

The laws were passed with the support of all three parties in the Assembly.

Canberra Liberals' legal affairs spokesman Jeremy Hanson said the laws were: "not so broad to be draconian but wide enough to be effective".

However because no harm will have to have occurred for someone to face the maximum penalty, Mr Hanson urged "caution" in how the laws were applied.

Greens MLA Shane Rattenbury said the laws sent a strong message that drink spiking was "unacceptable".

Domestic violence prevention minister Yvette Berry said one-third of drink spiking incidents led to sexual assault.

She said she hoped the law would make victims more likely to come forward faster.

She said those delays currently made it difficult to collect the evidence needed to successfully prosecute offenders.