Union officials say the "recommendation" does not bind English tax judges.
The union's latest sport classification battle is centred on tax. It argues that bridge - a game played by four players in two competing partnerships - helps stimulate the mind, particularly in older people.
Advocate General Maciej Szpunar said in his advice on a case pitting the English Bridge Union against British tax authorities that to be a sport within the meaning of the VAT system "a physical element is not necessary".
Szpunar stressed contract bridge is internationally accepted as a sport, in particular by the International Olympic Committee in 1998, and will be offered at the 2020 Olympic Games.
The case will be reviewed by ECJ judgesin the autumn.
While the advocate general's comments are not binding, judges follow them in most cases. The EBU argued it ought to be able to reclaim money under EU VAT exemptions for sporting supplies because of the mental strain required for bridge.
Jeremy Dhondy, the EBU's chairman, said the finding was "a vindication of our view that bridge should be regarded as a sport with all the advantages that brings both for bridge as a game and also for our members and prospective members".
Different countries have different opinions on whether bridge is a sport.
The 2011 Charities Act adopted a definition of sport as "activities which promote health involving physical or mental health or exertion", which specifically included "mind sports".