Blunt Object discusses the similarities and divergence of liberalism and libertarianism, yadda-yadda.
The reply in the comments from perlhaqr demands reposting:
[The problem with this otherwise laudable motivation is,] liberalism sets up government specifically as the biggest kid on the block and assumes away the need for any other institution to hold power over it to keep it in line. The very existence of a sovereign regulatory body suggests that powerful actors (occasionally) need to be bullied into behaving themselves, but the only provision for bullying that sovereign body into behaving itself is a vague wave of the hand at "elections" and "democracy". Sure, that works well in this best of all possible worlds. Quis custodiet ipsos custodes?
*contemplates a new t-shirt design*
"Ego custodiet, motherfucker."
[I happen to agree with the Object, BTW; the largest individual failing I generally identify when talking to liberals is the belief that voting is sufficient to keep abusive governments in line, no matter how hard it fails in the real world. "Sure, it's an abusable power we're handing government, but if they abuse it, we'll just vote them out in four years!" "Uh-huh. And how'd that work out for killing Bush's Patriot Act?" "..."]