Employment law experts have expressed concerns about plans to fast-track decisions on disputes before the Employment Relations Authority.

Among sweeping changes proposed in the new Employment Relations Amendment Bill, the authority will have to give a verbal determination at the end of its hearing, followed by a written record within three months.

Alternatively it must provide an indicative determination subject to additional information being received, then a final finding three months after getting the extra detail.

Susan Hornsby-Geluk, a partner at Dundas Street employment lawyers in Wellington, agreed a decision should be delivered within three months, but not with the requirement for a verbal determination at the end of a hearing.

"Many authority hearings are complex and lengthy - they could last up to a week with multiple witnesses and volumes of documents; and to expect the authority member to digest that and then deliver a sensible and reasoned decision is a huge ask.

"My concern is that it's going to lead to less robust decision making and also a feeling on the part of the parties that they haven't been properly heard.

"You might find whilst you get through the authority process more quickly, you end up with more appeals to the Employment Court, as people don't feel they've had an adequately reasoned decision," she said.

Employment lawyer Peter Cullen said it didn't make sense to provide an indiction after a hearing when the additional information hadn't been received.

"The objective of the minister to get quick decisions out is a good one, but there may be some fish hooks in the wording, particularly around the more documents part - I would've thought you'd be better off getting the document before you conclude the hearing."

Labour Minister Simon Bridges, who introduced the bill to Parliament today, said the changes would ensure parties get a resolution more quickly.

An immediate verbal determination would give the parties an opportunity to consider their respective positions and whether they may wish to settle their dispute between themselves, without waiting for the authority to issue the final written record.

Other proposals in the bill include allowing up to 10 per cent of pay to be docked when workers refuse to carry out some of their duties in protest at conditions and the end of employees having to be covered by a collective agreement for their first 30 days in a new job.

The Council of Trade Unions president Helen Kelly said the bill undermined the collective bargaining process.

The CTU would campaign for employment laws that encourage collective bargaining as the way to higher wages and productive and safe workplaces, she said.

About 13 per cent of New Zealand workers are covered by a collective agreement, 9 per cent of private sector workers and 58 per cent in the public sector.

Other changes signalled before the last election included the employer being able to determine when rest breaks are taken if an agreement cannot be reached with the employee.

- APNZ