People driving or operating vessels in Jersey waters will be required to take a breath test if they're caught driving carelessly under new maritime rules agreed by the States Assembly.
Politicians have agreed changes to harbour regulations regarding inshore safety, which will come into effect on Tuesday, 18 November.
They introduce penalties for those found guilty of causing harm to others within Jersey's territorial waters.
They also introduce specific aggravated offences in circumstances where the skipper is under the influence of drugs or alcohol.
It will mean the Harbourmaster or police can require a sample of breath where a skipper is suspected of driving carelessly or dangerously.
However, Deputy Kirsten Morel says random breath tests will not be introduced.
"This offence will allow for breath testing based on suspicion of careless behaviour, without the evidence or suspicion of injury or fatality.
"The aim is to avoid penalising responsible operators. There is no evidence of a consistent problem of people dangerously operating vessels whilst under the influence.
"Thus, I'm not introducing random breath tests, making the offences proportionate to the level of risk.
"Enforcement will be based on reasonable grounds for testing. This approach mirrors that of other jurisdictions, including the UK and Guernsey."
The majority of States Members backed the proposed changes to the law, which has been described as a 'measured approach'.
Deputy Kirsten Morel says, similarly to under the Road Traffic Law, officers will not be able to breathalyse people without reasonable suspicion.
"To support joined-up working between Ports of Jersey and States of Jersey Police during the course of maritime investigations, the two parties have agreed and signed an enforcement Memorandum of Understanding (MoU).
"While our waters are currently not deemed unsafe, [this} will provide clarity on acceptable and unacceptable conduct, providing greater accountability for all sea users, helping to prevent incidents before they occur."
In September, the Minister approved the purchase of approved breathalyser devices, the Dräger Alcotest 7000 and 6820, by Ports of Jersey.
A scrutiny panel led by Deputy Montfort Tadier, which reviewed the legislation, said it remained concerned about the lack of detail around who would be responsible for policing and enforcing the law.
"We feel that the current MoU contains some significant gaps in this regard, and, despite several requests, we are disappointed to see that they are yet to be addressed."

Parked cars damaged in Victoria Avenue crash
L'Ecume II: Lewis Carr jailed for 20 months for fatal collision at sea
Guernsey's former Chief Minister admits making indecent images of children
Minister approves 42 sheltered homes at nursing home
Jersey potato farm to be the site of Channel Islands' largest roof solar array
Emergency work on Bagot Road due to suspected gas leak
Jersey court to allow sentencing remarks to be filmed
St Saviour to get new public park