While B.C. signed the New West Partnership Trade Agreement in 2010 pledging to «remove barriers to trade, investment and labour mobility» between western provinces, Clark's demands pose the biggest barrier to
interprovincial trade this country has seen for a long time.
In coming to this decision, the Supreme Court confirmed that s. 121 of the Constitution Act, 1867 prohibits laws whose purpose is to «restrict or limit the free flow of goods across the
country,» but that «laws that pose only incidental effects on
trade as part of broader regulatory schemes not aimed at impeding
trade do not have the purpose of restricting
interprovincial trade and hence do not violate s. 121.