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Changes in U.S. politics have caused shifts in the theoretical purposes of sentencing. During the heyday of liberalism in the 1960s and 1970s, the judicial and executive branches (for example, parole boards) wielded power in sentencing. Legislators designed sentencing laws with rehabilitation in mind. More recently, during the politically conservative 1980s and 1990s, legislators seized power over sentencing, and a combination of theories—deterrence, retribution, and incapacitation—have influenced sentencing laws.