The Supreme Court on Tuesday is scheduled to consider whether some states should be held responsible for controlling air pollution that floats past their borders and, if so, by how much and by whom between the federal government or the states.

At issue is the Environmental Protection Agency's Cross-State Air Pollution Rule. The court will hear 90 minutes of oral arguments on the rule, which a lower court rejected in August 2012 on the grounds that the EPA didn't give states enough time to craft their own plans and required some to reduce more than their fair share of emissions.

And not far from the Supreme Court, the U.S. Court of Appeals for the District of Columbia Circuit will tackle another Obama administration emissions rule, this one power plant emissions governing mercury and other air toxics.

The cases underscore the hard line the Obama administration has taken on air pollution, whether of the greenhouse gas or air quality variety.

The cross-state air pollution rule, which was never implemented, would require as many as 28 "upwind" states in the Midwest and South to curb ozone and fine particle emissions at power plants, which contribute significantly to ozone pollution in the Northeast and Mid-Atlantic. Those pollutants can cause heart and respiratory problems, such as asthma, and sometimes lead East Coast states to violate federal ozone standards.

East Coast states want their Midwest and Southern counterparts to adhere to that "good neighbor" clause, contending they have done as much as they can to curb pollution in their own states by requiring emissions-control technology for power plants. Eight of them filed a separate petition Monday asking the EPA to force Midwest and Southern states to more aggressively tackle ozone pollution.

The onus is on the EPA to garner support from five of the eight justices involved, as Justice Samuel Alito is expected to recuse himself as he did when the court was considering whether to hear the case.

That won't be an easy task, said David Marshall, senior counsel with the Clean Air Task Force, which is helping defend the rule.

"I think the main issue is that developing a rule that appropriately reduces the interstate transportation of air pollution is by its nature very complicated," he said.

The court could be headed for a 4-4 split decision that would leave the decision by the U.S. Court of Appeals for the D.C. Circuit intact, said Jeff Holmstead, a former EPA assistant air administrator under George W. Bush.

"As you look at the justices and you look at the arguments, it's hard to see how the government gets to five votes," said Holmstead, who now represents energy and industry firms at Bracewell & Giuliani.

The EPA will argue that the appeals court didn't have the right to review complaints from the states, contending the issues that opponents raised should have been addressed earlier in the rule-making process.

But success on that front is unlikely. That means the Obama administration must convince justices that states knew all along they needed to devise a plan for slashing cross-state pollution and that the method the EPA used to calculate each state's contribution to emissions was sufficient.

That will be a difficult needle to thread, said Jennifer Macedonia, a senior adviser with the Bipartisan Policy Center think tank.

While the Clean Air Act -- the underlying law for the rule -- grants the EPA authority to regulate cross-state emissions, federal courts said a previous attempt to calculate individual state contributions under former President George W. Bush's administration didn't go far enough. The appeals court said the Obama administration's went too far.

Part of the problem is accurately mapping from where emissions originate and then settle. The EPA has computer models for doing so -- which the agency relied on with this most recent rule-making attempt -- but that didn't get to the level of detail to satisfy the appeals court.

"There's a reason they haven't found a way to do it molecule by molecule. It's hard to a imagine a way of doing that," Macedonia said. "But does that mean, because the act is written that way, that the EPA should be given some discretion in the methodology they develop to apportion each upwind state's obligation to reduce pollution that blows into another state?"

States and energy firms that filed the lawsuit against the EPA also argued that the agency didn't give states time to devise plans to address the emissions in question.

Republican Oklahoma Attorney General Scott Pruitt, who heads the Republican Attorneys General Association, said in an email that the rule is an example of the EPA "attempting to deny the states their proper role in crafting state solutions to address environmental issues."

Opposing states contend the EPA did not establish a separate emissions-reduction target for cross-state pollution before requiring them to submit individual state implementation plans for meeting air quality standards. Usually, they said, the EPA identifies that target and then gives states 18 months to formulate a plan.

The EPA, however, contends its policy always has been that states need to figure out their cross-state pollution contribution and include it in the full state implementation plan. When states didn't address those pollutants in their implementation plans, the EPA said it had the right to impose the federal standard.

But Holmstead called that a "change in tune" for the EPA.

"This is the first time that the EPA has taken the position that states knew all along what they needed to do," he said.