It's the most important day of the Supreme Court's three-day review of President Obama's health care bill. And by extension, that makes it one of the most important days in the last decade of Supreme Court hearings—or as The New Yorker's legal wiz Jeffrey Toobin puts it, the biggest day since Bush v. Gore: "Pay attention, folks." Here are the justices, the arguments and the media to keep track of today as the high court weighs the constitutionality of the Affordable Care Act.

The arguments They key issue at play today is Obamacare's individual mandate, or whether the government has the right to force individuals to purchase health care. The Obama administration says it does because this is well under its powers to regulate interstate commerce, notes the Associated Press. And because health care takes up nearly 18 percent of the national economy and signing up healthy people alongside sick people is necessary to afford covering everyone, the mandate is legally OK. The law's challengers say compelling citizens to buy stuff whether they use it or not, be it health insurance or popsicles or Nerf guns is unconstitutional. Additionally, the Constitution's idea of federal taxation is not penalizing people for not buying insurance. 

The justices We've known the main arguments for awhile now but the big moment is going to be hearing the justices react to these statements, notes The Washington Post's Greg Sargent. The exchange to watch for is Paul Clement, the lawyer arguing against Obamacare, saying the individual mandate paves the way for an unprecedented intrusion of the federal government into all citizens' lives.  That's the point that a number of lower courts have nodded along to and "Obamacare’s defender will closely monitor the reaction to this argument from justices Roberts, Kennedy, and Scalia. If one or more of them greet it with skepticism and subject it to sharp questioning — for instance, by pointing out that the health care market is unique, because everyone must ultimately partake of health care — that’s good news for Obamacare proponents," writes Sargent. 

The second exchange to watch out for will be the justices' response to Obama administration lawyers explaining what can't the government do if it has the power to enforce the mandate. Obama lawyers will say the government can't do a lot of things, like regulating family law, education or general criminal law. But health care is special because the feds already regulate it and it soaks up so much of the economy already. "If they react with skepticism, that could be trouble," writes Sargent,  "because it means they are prepared to accept the idea that the mandate assumes no 'limiting principle' over federal power." As always, Justice Kennedy will be a hugely important figure to watch, as the Reagan-appointed justice typically provides the swing vote for either the left or the right and is famously difficult to predict.

The media. For uber wonky analysis, the indispensable SCOTUS Blog and the ACA Litigation Blog. For a conservative take, the American Spectator's Philip Klein. For a liberal take, The New Republic's Jonathan Cohn. Politico scribes Kate Nocera, who's already taking snapshots of demonstrators outside of the high court, Jason Millman and Jennifer HaberkornThe New Yorker's and CNN's SCOTUS expert Jeffrey ToobinNational Journal's Jill Lawrence and Naureen Khan. And of course, stay with us for coverage throughout the day.