However one idea that has come up again and again in twitter is that you cannot be philosophically libertarian and support the death penalty.
For example I've done a quick search and lifted a few tweets:
The incoherence of supposed libertarian @GuidoFawkes supporting the death penalty (which costs more than life imprisonment) is hilarious
I'm a pro-death penalty libertarian! I'll let the state kill me, but God forbid I give them any money(I've left off the names, but searching on twitter should find them if interested.)
Genuinely don't understand this death penalty campaign from @guidofawkes. If you don't trust the gov to tax you, why trust it to kill you?
This seems based on a fundamental misunderstanding of libertarianism. A strawman is being constructed that a libertarian doesn't trust the state to do anything.
Libertarianism is about maximising some measures of liberty. I think these measures are limited and ignore other limits on freedom, which is why I am a Liberal and not a Libertarian.
However these measures of liberty include restrictions on the actions of others: they cannot act to reduce your liberty: for example by stealing your money. I imagine very few libertarians would say that freedom to murder is a freedom they want to protect.
Libertarians do not want abolition of state (that is a form of anarchism), but the minimising of it. From those I've read bits of this would include a military and a justice system. Once you accept the need for a justice system, including courts, then you accept the need to punish people by restricting their liberty in some way. This is entirely consistent with Libertarianism.
For example the US Libertarian party platform says
Government exists to protect the rights of every individual including life, liberty and property. Criminal laws should be limited to violation of the rights of others through force or fraud, or deliberate actions that place others involuntarily at significant risk of harm.Acknowledging the need for some government, albeit a minimal one.
Once you have courts the decision to execute or not can be entirely orthogonal to the size of the state you want. If you believe (wrongly in my view) that executing reduces the murder rate then executions could be justified to maximise liberty of others.
The top one is especially silly: Libertarianism doesn't have to be about doing things on the cheap for the sake of it, and besides capital punishment doesn't have to be more expensive then life imprisonment.
So can we leave off the misplaced personal abuse of Paul Staines: play the ball and not the man. Lets win the debate. It is too important.