Select committees have the (theoretical) power to compel attendance - or find you in contempt of Parliament and lock you up. This is not a power they ever use, or even threaten to use. But it is there.
They're also now a lot more independent than they used to be, as the whips have a lot less influence on who gets on them, and who gets to be chairman.
But their power is only in calling and grilling witnesses in public and then writing reports that can make headlines. They can make recommendations, but that's as far as it goes.
Also they're somewhat constrained as to how partisan they can be. In that their report will lose a lot of its "moral force" if a chunk of the committee dissent, and produce a minority report.
It's a reasonable system, in that it gives a non-government controlled way of running enquiries - and looking at the effectiveness of new legislation after a few years. And often when that's done in a non-partisan way, those conclusions will make their way into amendments to that legislation. It also gives a career path to the more "troublesome" or individual types of MP - if they're a bit too maverick to go the PPS, junior minister route. Which improves the diversity of Parliament and allows those with expertise to have influence without having to join the government and thus vote according to the whip.
Biting the hand that feeds IT
