Check out Ken Simons's Creeping consequentialism and insidious economics, part I over at Prawfs. Here's a taste:
You are teaching or analyzing legal rule A. Suppose rule A seems to express an underlying standard of undesirable or impermissible conduct C. For example, the legal rule is: "D must pay compensatory damages to P when D's unreasonably risky conduct harms P." The underlined phrase expresses a norm of impermissible conduct.
Unthinking consequentialism can creep in at both levels of this analysis--in your analysis of what counts as creating an unreasonable risk to others, and in your analysis of whether a legal rule expressing this standard of conduct is normatively desirable. This danger is especially pronounced in analyzing tort doctrine, but it arises elsewhere, too.