Last week, the Obama administration put the finishing touches on a new policy that would deprive recipients of disability insurance and Supplemental Security Income (SSI) of their Second Amendment rights. The administration will now characterize those citizens as "mental defectives," thereby having their ability to own a firearm subject to the federal Gun Control Act.As Sheild put it, Obama has no problem emptying out Guantanamo Bay of dangerous terrorists and commuting the sentences of criminals that include those who broke federal firearms laws, but he doesn't like law-abiding American citizens possessing firearms.
Supplemental Security Income helps blind, disabled, and elderly people with little to no income. Previously, it was understood that "mentally defective" referred to one's mental health. Citizens who have been institutionalized against their will are restricted from owning a firearm. The new definition of "mentally defective" has nothing to do with being mentally ill.
Update: Dr. John Lott has more on this at National Review.