The conservative legal challenge to President Barack Obama's executive action on immigration, in line for U.S. Supreme Court review, would force the justices to wrestle with their own conflicting votes on when states have a legal right to sue the federal government.
It is a question the court would have to answer before it could rule on whether Obama exceeded his presidential powers, as 26 Republican-governed states led by Texas contend, by bypassing a gridlocked Congress and taking unilateral executive action aimed at shielding millions of illegal immigrants from deportation.
The case represents another conservative challenge to one of Obama's top policy priorities to come before the Supreme Court.
The justices could decide as early as January on whether to hear the dispute during their current term, which runs through June. If they do, they would have to decide how much weight to give the court's 2007 decision in a major environmental case.
The court was split on ideological lines in ruling 5-4 that Democratic-leaning states led by Massachusetts could sue Republican former President George W. Bush's administration in a bid to spur U.S. action on climate change. The ruling eventually led to the Obama administration issuing the first-ever U.S. greenhouse gas emissions regulations.
In that case, the liberal justices voted in favor of the states and conservatives dissented. This time, it will be conservatives asking the court to rule that states can sue and liberals arguing the opposite.
The Obama administration said on Tuesday it would seek Supreme Court review after an appeals court ruled in favor of the states challenging the November 2014 order, affirming a lower court's order blocking Obama's action.
In Monday's decision backing the states, the 5th U.S. Circuit Court of Appeals spent seven pages analyzing the environmental case and cited it throughout the ruling.
Seven of the current nine justices participated in the 2007 case, including frequent swing vote Anthony Kennedy, who backed the states.
Elizabeth Wydra, a lawyer with the liberal Constitutional Accountability Center, said conservative and liberal justices alike will be concerned about "courts becoming the battlefield for political disputes" by allowing states to challenge a broad range of federal actions.
Josh Blackman, a South Texas College of Law professor who wrote a brief to the appeals court backing the challenge to Obama, said conservative justices may find the potential harm suffered by states if the president's actions take effect is "more concrete" than the claim made by states in 2007 that were concerned by climate change's future impact.
