Australia gave millions of workers the legal right to "disconnect" on Monday, allowing them to ignore unreasonable out-of-hours contact from employers, to the distress of big industry.

People can now "refuse to monitor, read, or respond to" their employers' attempts to contact them outside work hours -- unless that refusal is deemed "unreasonable".

The law is similar to legislation in some European and Latin American countries.

Unions welcomed the legislation, saying it gave workers a way to reclaim a level of work-life balance.

"Today is a historic day for working people," said Michele O'Neil, president of the Australian Council of Trade Unions.

"The union movement has won the legal right for Australians to spend quality time with their loved ones without the stress of being forced to constantly answer unreasonable work calls and emails," she said.

"Australian unions have reclaimed the right to knock off after work."

But the reforms got a cool welcome from Australian industry.

"The 'right to disconnect' laws are rushed, poorly thought out and deeply confusing," the Australian Industry Group said in a statement.

"At the very least, employers and employees will now be uncertain about whether they can take or make a call out of hours to offer an extra shift," said the country's peak industry group.

The law, enacted in February, came into force for medium-sized and large companies as of Monday.

Smaller companies with fewer than 15 employees will be covered from August 26, 2025.

"We encourage workplace participants to educate themselves on the right to disconnect and take a commonsense approach to applying it within their workplace," said the head of Australia's workplace relations regulator, Fair Work Ombudsman Anna Booth.

Under the law, workers may be ordered by a tribunal to stop unreasonably refusing out-of-hours contact, and employers likewise may be ordered to stop unreasonably requiring employees to respond, it said.

The question of what is reasonable will "depend on the circumstances", the Fair Work Ombudsman said in a statement.

Deciding factors may include the reason for the contact, the nature of the employee's role, and their compensation for working extra hours or being available, it said.

France introduced the right to disconnect in 2017, hoping to tackle the "always on" culture facilitated by smartphones and other digital devices.