Article 20
1\. An employer may bring proceedings only in the courts of the Member State in which the employee is domiciled.
2\. The provisions of this Section shall not affect the right to bring a counter-claim in the court in which, in accordance with this Section, the original claim is pending.
Petronas Lubricants Italy SpA v Livio Guida
Article 20(2) of Regulation No 44/2001 lets an employer bring, before the court already properly seised of proceedings started by the employee, a counterclaim based on a claim-assignment agreement concluded after those original proceedings were brought between the employer and the original holder of the claim.
Holterman Ferho Exploitatie BV and Others v F.L.F. Spies von Büllesheim
Where a company sues a person who acted as its director and manager in order to establish misconduct in the performance of those duties and obtain redress, Chapter II, Section 5 (Articles 18 to 21) of Regulation No 44/2001 precludes the application of Article 5(1) and (3) - provided that, in that capacity, the person for a certain period performed services for and under the direction of that company in return for remuneration, which is for the referring court to determine.