The bill comes after data last year revealed a huge unexplained jump in emergency mental health detentions.

Under current laws, police and paramedics can detain someone in order to take them to hospital if they believe the person has a mental illness and is likely to inflict serious harm on themselves or others.

The proposed laws would increase the threshold under which police and paramedics may arrest someone under the act.

It would mean people would not be apprehended if they agree to medical assistance.

Police and paramedics must also be satisfied the person requires urgent medical attention and that the risk of harm is immediate.

Someone who is subject to a detention order would be able to seek a review by ACAT under the proposed legislation.

Mental Health Minister Shane Rattenbury said the changes to the laws would be delayed to allow sufficient time for ACT Policing and the ACT Ambulance Service to provide education and training.

"This section is a rare example of legislation that can lead a member of the community to be deprived of their liberty on mental health grounds," he said.

"For this reason, it is essential that sufficient safeguards are in place to balance what can be competing priorities of safety and liberty.

"Should someone be apprehended under [the mental health act], whilst it may be a relatively short period of time, it still represents a deprivation of their liberty and this may have long standing impacts for their personal matters.

"When someone agrees that they require immediate healthcare or assistance, they should not be penalised for their help-seeking behaviour and a decision to apprehend on those grounds is likely to be disproportionate."

Last year, The Canberra Times reported there had been a huge increase in emergency detention orders issued by paramedics in 2018-19.

The fourfold jump was largely unexplained when questions were put to the Emergency Services Agency.

But chief psychiatrist Denise Riordan said the jump appeared to be due to "literal" interpretations of the legislation.

She claimed well intentioned paramedics had used the orders to help get a patient seen promptly at Canberra Hospital.

Patients brought in under the mental health act have to be seen within four hours to comply with legislation.