Digby at Hullabaloo is right on the mark when it comes to analysis of Bush's Supreme Court picks:
Harriet Miers is the official machine justice, a made woman, the one whose only committment and loyalty will be to Karl Rove and George Bush.
[W]hat [Bush and Karl Rove] are most interested in is getting someone on the court who will not independently decide that the interests of democracy require that they vote against whatever GOP electoral schemes come down the pike. There can be no daylight on that. Miers can be guaranteed to do what is best for the GOP.
What Digby doesn't mention is that this argument applies not only to Miers, but very likely to Roberts as well, the bulk of whose career was spent in the service of the Republican party.
Of course, as we learned in December 2000, there already were 5 Supreme Court justices ready to perform this role. All that has happened now is that the reign of the machine justices has been extended by two or three more decades.