6 of the institution or enter its premises, lobbyists are factually required to adhere to these rules.15 The rules could therefore be characterized as de facto binding. It should be noted, however, that the regulatory impact of an institutional register depends on the actual implementation. For example, if access to an institution can also be granted to individuals who are not registered on an ad hoc basis as in the case of the German Bundestag or the European Parliament, the impact of the register can be weakened. Mandatory legislation on lobbying encompasses binding laws and regulations which are applicable to all individuals or institutions engaging in lobbying activities. The approaches in the United States and Canada are the usual reference points in this context, but recently similar approaches have been taken in a number of European countries such as Austria, Lithuania, Poland and Slovenia.16 Even though these laws differ in terms of their scope and regulated activities, they share a binding and mandatory nature which is imposed on all individuals engaged in the relevant lobbying activity. Compliance with these laws can be enforced through the standard forms of regulatory sanctions including fines and in some cases even imprisonment. 2.2. THE TRANSPARENCY REGISTER OF THE EUROPEAN PARLIAMENT AND THE EUROPEAN COMMISSION OF 2011 The current approach of the European Commission and the European Parliament belongs to the second group of institutional registers. It is a non-mandatory register based on an interinstitutional agreement between the EP and the Commission.17 Interinstitutional agreements have similar legal consequences as Rules of Procedure of the respective institutions. They are binding on the institutions and can therefore have similar factual binding effects on lobbyists if they interact with the respective EU organs. However, an interinstitutional agreement cannot establish any formal binding obligations on individuals in the same way as mandatory legislation. It should also be noted that the Transparency Register does not extend to the Council and lobbying activities towards this institution. The Transparency Register of the EP and the Commission can be compared to the voluntary registers in some EU Member States such as Germany, but it is unique as it covers two institutions (Commission and Parliament) and not just one as in the case of the German Bundestag’s register. 15 Report on conclusion of an interinstitutional agreement between the European Parliament and the Commission on a common Transparency Register, A7-0174/2011, 26 April 2011, p. 23 16 Kalni?š, above note 6, p. 4 17 The legal basis for interinstitutional agreements is Art. 295 TFEU.