The statement comes as Colorado and Washington await word on how the Justice Department will respond to passage of laws in each state that legalize the sale of marijuana. The practice is banned under the federal Controlled Substances Act.
Gupta was widely reported as under consideration for nomination as surgeon general after President Obama's election in 2008, before ultimately removing his name from consideration.
“We have been terribly and systematically misled for nearly 70 years in the United States, and I apologize for my own role in that,” Gupta wrote.
Earnest said he was not sure whether Obama would be willing to take administrative steps to make it easier to conduct medical tests of marijuana.
"I'm not exactly sure steps are required or what changes could be implemented into the law to have an impact on marijuana research," he said.
But the White House spokesman wryly acknowledged that the subject garnered lots of interest.
"For some reason I have the sneaking suspicion that this is going to draw me all kinds of traffic on Twitter," Earnest quipped.