The state’s highest court has ruled that Massachusetts has failed to meet its legal obligation to set and enforce annual limits on greenhouse gas emissions.

The Massachusetts Supreme Judicial Court on Tuesday ruled the state hasn't met the requirements of the 2008 Global Warming Solutions Act.

In the case, the Conservation Law Foundation, the Massachusetts Energy Consumer Alliance and four teenage plaintiffs had argued that the state Department of Environmental Protection failed to enforce the 2008 law, which established a goal of reducing emissions by 25 percent by 2020.

For the SJC unanimous ruling, Justice Robert Cordy wrote that the "unambiguous language of [the law] requires the department to promulgate regulations that establish volumetric limits on multiple greenhouse gas emissions sources, expressed in carbon dioxide equivalents, and that such limits must decline on an annual basis."

Lawyers for the state had argued that the law's requirements have been met, saying the law only calls on the Department of Environmental Protection to set "a desired level of declining" emission limits.

In a statement, Jenny Rushlow, the CLF's lead attorney on the case, called Tuesday "a historic day."

She added: "Today our highest court declared clearly and unequivocally that our leaders can no longer sit on their hands while Massachusetts communities are put at risk from the effects of climate change."

Rushlow told State House News Service that the DEP has discretion over which carbon sources to regulate, but not whether to regulate.

In a statement, a spokesperson for the Office of Energy and Environmental Affairs said the administration is reviewing the ruling and "remains committed to meeting the Global Warming Solutions Act goal ... as well as achieving greater reductions for 2030 and beyond.”

Tuesday's high court ruling vacates a Superior Court judge's ruling.

The decision follows an environmental group's report in February that found that the state is not on track to meet its 2020 emissions targets.

That report came a month after a state report that found Massachusetts is on track to meet its pollution goals, provided lawmakers approve of a plan to import more hydropower to the state.

Beacon Hill is currently debating comprehensive energy legislation.

With reporting by the WBUR Newsroom, The Associated Press and State House News Service