How does the Contract Law definition of 'consumer surplus' relate to the Microeconomics definition?
O'Sullivan &amp; Hilliard write: Consumer surplus is a "type of non-financial loss" and


  can be defined as the amount by which the particular plaintiff values performance of a particular obligation over and above its market value.


This is identical to the economist's definition of consumer surplus.

Using Pindyck and Rubinfeld's example: If a student was willing to pay as much as $\$13$ for a rock concert ticket (this is the value she places on the "performance of a particular obligation") but only had to pay $\$12$ (this is the price or the market value of the ticket), then her consumer surplus is $$\$13-\$12=\$1.$$