Corporate spies bad; state spies good?

It's been great that's there's been a widespread outcry about corporations spying on political activists. But it'd be ever better if there was a similar outcry about the state doing exactly the same thing - after all the Security Intelligence Service has a long history of spying on leftwing activist groups and individuals. And in recent years the power of the SIS has been extended, with the help of MPs from Labour, National, the Maori Party etc. Anyway, Reading the Maps has an excellent post about The spies nobody's talking about. This asks, if it's wrong to use public money to spy, then where does this leave the SIS?