The fate of a lawsuit challenging Minneapolis’ 2040 Comprehensive Plan is now in the hands of the Minnesota Supreme Court, which heard oral arguments in the case Wednesday.

Three groups — Smart Growth Minneapolis, the Audubon Chapter of Minneapolis and Minnesota Citizens for the Protection of Migratory Birds — sued the city in December 2018, seeking to block the City Council from approving the document that will guide development in Minneapolis for years to come.

Their lawsuit was dismissed, and they are now asking the Supreme Court to reinstate the case. It’s too early to tell exactly what might happen if they prevail, though options could include asking a judge to require changes to the plan.

“They, first and foremost, want the environmental concerns that have been raised to be honestly identified and dealt with,” said Jack Perry, an attorney representing the groups.

He added that they also want other “deficiencies” to be addressed, noting that some of his clients are concerned about affordable housing requirements for developers.

Citing the Minnesota Environmental Rights Act, the group argued that the city should have done a more thorough environmental analysis before adopting the comprehensive plan, which allows for denser zoning throughout much of the city. They say an analysis conducted by their expert showed the plan could increase water and air pollution and cause other environmental problems. That analy­sis assumes there will be a “full build-out” of the comprehensive plan, which the city says has not happened.

The City Council passed the 2040 Comprehensive Plan in 2018 after a year of debate that drew thousands of comments of opposition and support. By doing so, Minneapolis earned national attention for becoming the first large city to eliminate single-family zoning citywide, as well as inviting denser development along transit corridors.

The plan allowed for a wide range of changes to the city’s development plan.

Some aspects of it, such as the move to allow duplexes and triplexes in areas previously reserved for single family homes, have already been implemented.

Others, such as updates to the “built form” policies that guide the design of buildings, are still in progress.

Speaking before the justices Wednesday morning, Perry argued that the plan gives people the ability to build denser units as a “matter of right.”

“There’s no discretionary approval down the road. As long as you satisfy the criteria down the road, you can have your residential development,” and the collective impacts of that have not been adequately accounted for, Perry argued.

The city of Minneapolis argues that its comprehensive plan is exempt from such reviews under the Minnesota Environmental Policy Act, and that environmental reviews should instead be conducted for individual projects.

Assistant City Attorney Ivan Ludmer told the justices he believed the “matter of right” argument was a “red herring” because the city still reviews permits for individual building projects.

“It’s not that any triplex gets approved,” Ludmer said. “If someone came to the city and asked to build a triplex made out of purely asbestos and lead, that would not be approved, and that would clearly have a greater difference, environmental effect than the triplex made from other materials.”

The justices do not have a deadline for handing down a decision in the case.

While some remained quiet for most of the hearing, others offered hints at their thinking.

Justice Natalie Hudson said at one point that she felt Perry had made a “strong argument” that the Minnesota Environmental Rights Act could apply in this case.

Justice Gordon Moore asked both attorneys for more detail on what they would envision happening next, if the Supreme Court decides to reverse the dismissal.