Article 19 Council Regulation (EC) No 44/2001 (Brussels I)

An employer domiciled in a Member State may be sued:
1. in the courts of the Member State where he is domiciled; or
2. in another Member State:
(a) in the courts for the place where the employee habitually carries out his work or in the courts for the last place where he did so, or
(b) if the employee does not or did not habitually carry out his work in any one country, in the courts for the place where the business which engaged the employee is or was situated.