Canada wanted a free trade pact with Europe. If it took place it would help dairy farmers sell their products in Europe.
Dairy farmers in Belgium thought the agreement would hurt their sales. They had enough power to stop their government from signing the agreement.
But then the governments signed the agreement. Advocates said it set a standard for new trade deals. If they are correct, global trade has won a great victory.
The purpose of free trade is to create bigger economies. The challenge is to not hurt local economies. New agreements have to deal with that problem.
Source: The New York Times October 30, 2016