Electronic Identities (eID) and their cross-border recognition are on top of the agenda of various e-Government initiatives of the European Commission (EC). Therefore, the EC launched the EU large scale pilot STORK, which was running for about 3.5 years and finished at the end of 2011. In this period, STORK has established a European eID interoperability platform for citizens. The focus of STORK was to achieve eID interoperability of natural persons. However, many e-Government processes are conducted by representatives of legal persons. Hence, this paper proposes an eID interoperability framework for the cross-border identification and authentication of legal persons or professional representatives using electronic mandates. The framework strongly bases on the findings of STORK and introduces an extension of the STORK framework supporting cross-border identification and authentication of legal persons.