LONDON (Reuters) - British Prime Minister Theresa May said it was possible that the European Court of Justice could continue to arbitrate trade disputes during a transition period after Britain has formally left the bloc in March 2019.  We want to have a smooth and orderly process of withdrawal ... that s why we want that implementation period and we have to negotiate what will operate during that implementation period, and yes that may mean we will start off with the ECJ,  May told parliament. The jurisdiction of the European court is a inflammatory issue for some Brexit campaigners within May s Conservative Party. Citing sovereignty as a benefit of Brexit, they argue that leaving the EU should offer supremacy to British courts. Britain also said it will seek to negotiate trade deals with countries outside the EU during a transition period, but it would not bring any such deals into effect if they clashed with the transition terms. In a document setting out its post-Brexit trade plans, the government said it would seek to  transition all existing EU trade agreements and other EU preferential arrangements  to provide continuity for exporters and investors. 
European courts could decide trade disputes during transition period: PM May