Junior doctors and paramedics are free to abandon the troubled Health Services Union and join another union after the NSW Parliament changed laws late yesterday afternoon to allow the change.

The state government was forced to compromise on its original plan to introduce new laws to allow anyone to join the union of their choice. Unions NSW, supported by Labor and the Greens, opposed the proposal saying it would lead to rogue unions being established.

However, they supported changing the law to allow junior doctors and paramedics to join another union. The doctors and paramedics have long complained the HSU has not represented their interests well.

NSW AMA president Brian Owler told the Herald yesterday: "We are delighted the junior doctors now have the opportunity for proper industrial representation and finally have a pathway out of the HSU."

Industrial Relations Minister Mike Baird said the government's original legislation aimed to provide choice to employees about the union organisation they joined.

"We on this side of the house are proud to support the option of choice rather than being dictated to about who you must join and why. That was the intent of the bill and it was also intended to harmonise the relevant provisions of the legislation with corresponding federal provisions.

"We haven't got there on that. But those in the other place have seen fit to amend it to make it more narrowly focused and that dilutes its original aims."

"While the bill doesn't go as far ... it does deliver the right outcome for at least two groups of employees that have been rightly demanding change for a long time."

Greens NSW MP and industrial spokesperson David Shoebridge said the amendments were important to protect organisations from competitive unionism.

"The O'Farrell government's plan was to have unions fighting among themselves, setting teachers against headmasters, nurses against midwives and one government department against the other," he said.

"The Greens recognise that paramedics and junior doctors have a legitimate case to seek separate representation from the disgraced HSU and we moved amendments to allow that to happen.

"However the Greens were not going to be part of the O'Farrell government's ideological attack on all unions and we limited the operation of the Act to paramedics and junior doctors."

NSW Health Minister Jillian Skinner said the change was good news for junior doctors and paramedics.

"At long last their calls for a greater choice in unions have been heard," she said.

"Both as shadow health spokesperson and as minister, I have heard their calls for a change and I'm delighted today that we have been able to deliver on our promise."