Hardly any other parliament has seen as many MPs switching their legislative party membership during legislative periods as the Polish parliament. This allows for a detailed assessment whether MPs switch their party to be more in accord with the positions defended by their party leaders, or if after a party switch, party discipline affects the ideological positions. Drawing on the complete record of voting by Polish MPs, the paper demonstrates that MPs' positions are strongly influenced by their legislative party membership.
1 Nils Weidmann and Silvia Makowski provided help in making the data used in this paper available and usable and the financial support of the Swiss National Science Foundation (Grant No 100012-111909) is gratefully acknoledged.
2 Département de science politique, Faculté des
sciences économiques et sociales; Université de Genève; 40, Bd du
Pont d'Arve; 1211 Genève 4; Switzerland; phone ++41 22 379 83 78;
email: simon.hug@unige.ch