In reality, however, libertarianism often requires unselfish behavior. Libertarians routinely condemn politicians who advocate statist policies in order to expand their power or ensure their reelection, bureaucrats who seek to increase the authority and funding of their agencies, businessmen who lobby for government subsidies and handouts, politically influential developers who use the power of eminent domain to acquire property that they covet, law enforcement officials who support the War on Drugs because it increases their funding, public employees unions who support big government in part because it increases their pay, and much other self-interested behavior. The fact that all of these groups are motivated, at least in part, by self-interest doesn’t prevent libertarians from denouncing them. That’s because libertarianism is a theory of the appropriate role of government in society, not a theory that judges the morality of human behavior based on whether or not people are acting out of self-interest.

via The Volokh Conspiracy » Libertarianism and Selfishness.