The Region of Waterloo is questioning the fairness of an Ontario Municipal Board ruling and wants to take the planning tribunal to court – again.

At the centre of the dispute is the region's official plan that sets limits on urban sprawl and guides growth over the next 20 years. The plan meets or exceeds recommendations for concentrated growth as defined in the provincial Places to Grow act, which was passed in 2006.

However, a group of developers wants hundreds of more hectares set aside for development than the region's plan allows. The OMB, an arms-length judicial body that decides disputes over planning in the province, ruled in favour of the developers in January.

Now, the region is raising questions about the fairness of that evaluation and alleges that OMB staff may have been swayed by a consultant during a private training session.

Rob Horne, the region’s planning commissioner, says the same consultant was a primary witness for the developers in their appeal proceedings, while those proceedings were already active.

"That really brings the question to us whether the process was therefore biased when members of the Ontario Municipal Board who received the training were also adjudicating the Region's case at the same time," said Horne.

As a result, the region is seeking a judicial review of the process behind the ruling. No date has been set for the ruling.

Horne said that the OMB decision runs counter to the region's vision for growth through 2031, and opens the door to urban sprawl.

"Since about 2002 the region has had a vision for growth, compact growth, protection of environmental growth, protection of groundwater, but maintaining that high quality of life," he said.

While the Places to Grow Act set a target that at least 40 per cent of new residential development should happen in existing neighbourhoods, the region set a more aggressive target of 45 per cent.

The region's push for a judicial review comes in addition to an appeal of the growth plan ruling.

In April, the province announced it would join the Region of Waterloo in an appeal of the OMB's decision in favour of the developers.

The region's plan sets aside between 70-85 hectares for developers, but a consortium of developers, including Activa Holdings Inc., Stonefield Properties Corp., and Northgate Land Corp., are pushing for a plan that would see 1,053 hectares opened up.