Catalyst Theory Restoration Act of 2015

This bill defines "prevailing party" for purposes of determining the meaning of provisions in federal laws, federal regulations, or any judicial or administrative rules that provide for recovery of attorney's fees to include a party whose pursuit of a nonfrivolous claim or defense was a catalyst for a voluntary or unilateral change in position by the opposing party that provides any significant part of the relief sought.

The bill prohibits this Act from altering special eligibility criteria: (1) established for prevailing defendants, or (2) contained in statutes that expressly limit or qualify who may be considered a prevailing party for purposes of that statute.