Ben Nelson's Important Principle

Ben Nelson (D-NE) says that there's an "important principle" behind his joining with Senate Republicans to block debate on finance reform. He mentions "big government," and "unconstitutional," and says that "it's just wrong." What he doesn't mention?

At the same time, Nelson acknowledged that Berkshire Hathaway had contacted him to say it would be "adversely affected" by the new derivatives legislation. In turn, Nelson said he raised those concerns with the Agriculture Committee.

Nelson's most recent financial disclosure form, filed last year, shows that he and his wife owned between $1.5 million and $6 million in Berkshire stock in 2008 -- by far Nelson's largest listed asset.

Important principles don't come cheap.