The United States is currently home to 2% of the world's population and 25% of its prisoners. Conditions in US prisons are harsh, prisoners are forced to work for private companies for almost no pay, and lives are ruined by disproportionately long sentences. In short, the system is broken.
The Obama administration should take action on all of these issues through two measures.
(1) Significantly reduce sentences for possession of "soft drugs" such as Marijuana, MDMA and LSD. The dramatic rise in imprisonment is largely due to the "War on Drugs" that began in the 80s.
(2) Take control of the 100+ privately owned prisons that profit off forced labor in prison. Prisons should not be incentivized to lock up more people in the interest of making money.