Policy positions are highly relevant for national party competition. Amongst others, they signal parties’ view on policy issues. These policy positions are externally used by voters for their voting decisions. For the internal party dynamics policy positions are relevant as well: They have an inherent function for party members’ identification and are used as reference for legislative decision-making. When policy positions and legislative behaviour dramatically mismatch, parties can lose credibility. A decreasing credibility can rise fundamental problems for parties because it enhances the possibility of electoral defeat and can therefore result in a loss of parliamentary seats or government office. Additionally, the organisational strength of parties can be weakened when party members choose to exit. While that interplay of these two party functions – position taking and legislative behaviour – is known for national party competition, it is less clear for national parties within the European multilevel system. Obviously, the necessity of coherence between national party positions and voting behaviour in the European Parliament diminishes when the lack of public attention towards European legislature is taken into account. However, today’s importance of European decision-making and the resultant adherence by national parties’ policy experts give hints that coherence across these two political levels may be more important than initially assumed. The paper provides a theoretical concept of coherence between national party positions and legislative behaviour in the European Parliament. This concept includes explanations of characteristics and relevance of coherence for the two-level situation. Moreover requirements for (in)coherence between the two party functions are theoretically inferred. The concept of coherence gives new insights into the interdependence of the national party organization and legislative behaviour in the European Parliament.
