David Axelrod, the top campaign strategist for President Obama, said that the Supreme Court ruling on Obamacare will prevent “free riders” from driving up health care costs, as he defended the mandate as a penalty, not a tax.

“[W]e shouldn’t have free riders in the system who drive up everyone healthcare [costs],” Axelrod said on MSNBC’s Morning Joe, recalling Mitt Romney’s defense of the mandate at the state level. “This is only for people who can afford insurance, don’t get it, and then end up in our emergency rooms, get free care and then drive up everyone else’s premiums,” he said of the individual mandate moments earlier.

“Whether you call it a mandate or a tax, what it is is a penalty of the sort I described before,” Axelrod said, after noting that the mandate would “apply to very few people.”

In making that argument, he emphasized an aspect of the mandate that caused the dissenting judges to argue that the mandate is obviously not a tax.

“That Section 5000A [of the health care law] imposes not a simple tax but a mandate to which a penalty is attached is demonstrated by the fact that some are exempt from the tax who are not exempt from the mandate — a distinction that would make no sense if the mandate were not a mandate,” Justices Kennedy, Scalia, Alito, and Thomas wrote in a joint dissent.

The mandate-or-tax debate between the justices is crucial because the court ruled that if the mandate were judged as a mandate, not a tax, it would be unconstitutional.