Can technology solve all our environmental problems, or do we also have to reduce our consumption? This question has been debated for a long time within environmental science circles and can, with regard to at least some environmental problems, be answered in the affirmative today. However, it is not enough if only some individuals reduce their use of environmentally relevant goods voluntarily (which is known as "sufficiency") to achieve overall sustainable consumption patterns. Sufficiency has to become an issue on a political level, too. There are, however, doubts about the possibility of reducing consumption by means of politics in a liberal state because of the potential restrictions to freedom involved. This book shows the necessity and ways of legitimating a sufficiency policy within liberal-democratic, wealthy states from a political and philosophical perspective. Furthermore, it discusses ways of implementing such a policy as well as their limitations. Finally, the author proposes a concept for a sufficiency policy.