A Canadian class-action lawsuit that could cost three large tobacco companies up to C$27bn is set to begin in Montreal.
Two sets of smokers are arguing Imperial Tobacco, JTI-Macdonald and Rothmans Benson and Hedges manipulated nicotine levels and hid research on the health effects of smoking.
It is the largest suit of its kind brought before a Canadian court.
The trial opens as six provinces plan to sue the companies for health costs.
A similar suit in the US led to major tobacco companies paying $246bn over 25 years for health-care costs.