Definition of black act:
(n) :
(UK, historical) An act of the Parliament of Great Britain passed in 1723 in response to a series of raids by two groups of poachers, known as the Blacks. It greatly strengthened the criminal code and specified over 200 capital crimes.
(n) :
(India, historical, derogatory) Act XI., 1836, of the Indian Legislature, which placed European subjects on a level with natives as to their subjection in civil causes to the British East India Company's courts, including those under native judges.