Prisons in the Unite States are operated under strict authority of both the federal and state governments as incarceration is a concurrent power under the Constitution of the United States. Imprisonment is one of the main forms of punishment for the commission of felony offenses in the United States. Less serious offenders, including those convicted of misdemeanor offenses, may be sentenced to a short term in a local jail or with alternative forms of sanctions such as community corrections (halfway house), probation, and/or restitution. In the United States, prisons are operated at various levels of security, ranging from minimum-security prisons that mainly house non-violent offenders to Supermax facilities that house well-known criminals and terrorists such as Terry Nichols, Theodore Kaczynski, Eric Rudolph, Zacarias Moussaoui, and Richard Reid. The United States has the highest documented incarceration rate, and total documented prison population in the world. As of year-end 2006, a record 7.2 million people were behind bars, on probation or on parole. Of the total, 2.2 million were incarcerated. More than 1 in 100 American adults were incarcerated at the start of 2008. The China ranks second with 1.5 million, though China has over four times the population of the US.