
Well, duh.
Case paperwork: http://caselaw.lp.findlaw.com/scripts/getcase.pl?court=US&vol=000&invol=08-22
Elizabeth Wydra really takes Roberts (and to a lesser extent Scalia) to task on Daily Kos: http://www.dailykos.com/storyonly/2009/6/9/740499/-Scalia-and-Roberts-Ignore-the-Constitution.
The facts of this case are so egregious that I'm really honestly baffled what the minority thought it was saying, other than "it will make things really complicated and we don't like things complicated so we'll let people get away with egregious crap so we don't have a lot of complicated lawsuits." I'll have to read the dissent in detail - the excerpts I've read are unconvincing. It's quite clear that Justice Benjamin was elected with the support of over $3 million in Massey Coal money - more than double the amount spent by every other contributor combined. It's also clear that he repeatedly refused to recuse himself in the face of calls from pretty much everyone from the ABA on down. His was the deciding 3-2 vote.
To give the minority some due, Kennedy's decision is going to require further decisions to clarify such phrases as "a significant and disproportionate influence." But such is the role of jurisprudence - to create interpretable standards such as these by which we differentiate legal behavior from illegal. In addition, Kennedy and the majority seem willing to place their own limits, setting a fairly high bar to which a situation would have to rise in order for recusal to be required or lack of recusal to be a cause for action.