Negative interest rates (NIRP) in Europe and Japan are a function of central banks out of control defending their country banking systems by cornering the market in so-called "risk-free" government bonds. The lack of lendable collateral in these economies at low rates is a function of poor fiscal policy (a.k.a. crony socialism), not a failure of the central banks since they are really only taking their cue from hopeless government leaders and entrenched, concentrated wealth pools, who own the banks. The utter failure of this scheme was predictable, and the repercussions on the country stock markets that have been affected are an appropriate market response. Likewise, both the EU and Japan currencies have suffered greatly in this race to the bottom.
Fast forward to a world in which the major reserve currency in the world today, the U.S. dollar, is positioned through Fed policy to have a negative carry interest rate, to all the holders of dollars throughout the world. Chaos is the predictable outcome. It is the equivalent of both a default on the U.S. debt, and a tax on all foreign capital which is funding the U.S. debt. Cue up a major flight to hard assets, like gold, and anything else bolted to the ground, and a major run on the U.S. debt. This issue is far more critical to the potential economic outcome of such a decision than the effect on U.S. savers who are hopelessly tied to the policy decisions of their brain dead elected, and appointed in the case of the Fed, leaders. The problem is, the U.S. people alone do not have the $6.1T in funds needed to fill the gap left if the foreigners leave town. And if they do, they probably don't want to give $100 to the government to get $99 back, or even less, every year.
If you want less of something, tax it. A NIRP direction in the U.S. is a stepping stone to an outright depression, not only in the U.S., but world-wide. The upcoming election is critical to making sure this path is not chosen by the U.S., assuming Obama doesn't make this his final nail in the coffin for the U.S. economy as he departs silently out of town.