How the United States confronts climate change will be decided whenever the Democratic Party regains control of the White House and Congress. But it may ultimately be Chief Justice John Roberts who decides whether they succeed.

Every major Democratic policy would need to survive scrutiny by the justices. So how would the Green New Deal fare if it reaches the high court? This isn’t an easy question to answer, partly because lawmakers have yet to draft a proposal. Early last month, Representative Alexandria Ocasio-Cortez introduced a resolution recognizing “the duty of the Federal Government to create a Green New Deal”; 90 House Democrats have cosponsored it, and multiple Democratic presidential candidates have expressed support for it. But the resolution lacks the specificity of a bill. In fewer than 2,000 words, it outlines the Green New Deal’s goals, which include not only net-zero greenhouse gas emissions and renewable-energy investment but a job guarantee, universal healthcare, and more.

While the resolution does not describe in detail how the government could achieve these goals, left-wing policy wonks have been working to fill in the gaps. Data for Progress, a progressive think tank with close ties to Ocasio-Cortez, released its own proposal for a Green New Deal last September. It provides a road map for what a legislative package could look like if Democrats win unified control in Washington—and thus serves as a useful guide for what the courts would have to wrestle with, once conservatives mount the inevitable legal challenges.

One of the Green New Deal’s key components is a familiar one: implementing the Clean Power Plan. The Obama administration unveiled the plan in 2014 to stave off a two-degree Celsius rise in global temperatures over the next century, which scientists warn would have a catastrophic impact on civilization. The plan called for drastically curbing greenhouse-gas emissions from power plants, namely those powered by coal, and was meant to persuade other countries to put forth their own plans ahead of the Paris climate summit later that year.

The plan was soon challenged in court, and in 2016 the Supreme Court blocked it from going into effect until the legal questions were resolved. Justice Antonin Scalia’s death a few days later effectively tied the plan’s long-term fate to the outcome of the presidential election later that year. After Donald Trump took office, his first EPA administrator, Scott Pruitt, began the process of repealing the Clean Power Plan. The agency’s proposed replacement, unveiled last August, would shift much of the discretion to regulate coal-plant emissions to the states. (The legal challenges to the plan are on hold until the replacement process is complete.) Data for Progress’s proposal would revive the plan, as well the legal challenges to it.