Mr and Mrs De Gucht hope to prevent Belgian tax inspectors from gaining access to their bank accounts. Mr De Gucht is the current Trade Commissioner.
The couple have been at loggerheads with the Belgian tax authorities for some while. The tax inspection is seeking access to their bank accounts on the basis of legislation that became operational last July.
The couple is refusing to do so and have taken the matter to court in Ghent. Mr De Gucht wants Belgium's Constitutional Court to say whether or not the new law that relaxes Belgian bank secrecy legislation is constitutional.
The EU commissioner claims that the legislation is sloppily drawn up and violates people's privacy.
The law was enacted in response to pressure from abroad and fears that Belgium could become a tax haven!
News of the lawsuit only leaked this weekend. Mr De Gucht says it's a private matter, but Flemish socialist lawmaker Dirk Vandermaelen suggests the EU commissioner is keeping rather suspect company: Antwerp diamond traders who were caught with undeclared funds in Switzerland.