As Harbridge notes in the concluding chapter of this study, historically, for some political scientists, strong parties and party leaderships have been viewed as the solution to overcoming the obstacles to effective governance in a separated system. Powerful party leaderships, with their membership in tow, promised possibilities for the passage of ambitious legislation, yet the experience of the modern system was that such party government only occurs sporadically and was “conditional” on offering the rank and file reason to voluntarily fall into line.

Since at least 1995, however, party leadership appeared to have significantly strengthened in both House and Senate. The result, though, has not been the emergence of effective party government but one of gridlock driven by an increased partisanship that often seemed as much an end itself as a means. Despite persistent small majorities and frequent divided government, both parties seemed to have shunned bipartisanship even though the result has been inaction and government shutdown. Harbridge, in this interesting and well-researched text, looks at the House of Representatives between 1973 and 2004 and asks the titular question: is bipartisanship dead? The answer she arrives at is: it depends where you look.

The first issue that Harbridge tackles is the important question of how one measures partisanship within the chamber. The two most common approaches – by looking at the number of party-unity votes on legislation or using techniques such as DW-NOMINATE to identify where individual members sit ideologically – rely on the same data set: roll-call votes. The problem with this, as the study points out, is that members can only vote on the questions presented to them on the floor and, as such, a partisan floor strategy by the leadership (favouring legislation with little minority-party support) will show a partisan membership, even if that was not many members' preferred position. This point has been made before but it is necessary for the discussion and is well made here.

Harbridge instead looks at cosponsorship of bills as a way of judging the level of bipartisan behaviour in the House. She finds that while roll-call votes indicated a marked decline in cross-party support for legislation, cosponsorship behaviour suggested that bipartisanship in the pre-floor stages was much more resilient than the headlines would suggest. In this way impressions of a partisan House were largely a product of the leadership's floor agenda. The study also confirms expectations that legislation with bipartisan support in this period was more likely to become law than that which had little cross-party support.

The next question is why this is happening. The study posits a model of “strategic partisan agenda-setting,” within which is the argument that party leaders have often conflicting goals of building a record of legislative success (for which pursuing a bipartisan agenda would be beneficial) while also building a party brand distinct from their opponents (which lends itself to focussing on a more partisan legislation). That leaders favoured the latter at the expense of the former, or were able to, Harbridge argues, is partly a result of district “sorting” – that members' constituencies in this period were becoming more politically homogeneous.

The limit to this analysis is that the study remains largely focussed on events within the House and on what can be measured. That House leaderships have increasingly pursued partisan strategies must be seen in a wider political context where compromise and cooperation have become risky political paths. To her credit, Harbridge makes nods to the wider context, and makes no claims that the study here is more than only one part of the picture.

The period under consideration also pre-dates the Obama years; since 2009 partisan behaviour in Congress has hit a new high and legislative activity has plunged to a new low. Those years are given a brief analysis in the final chapter and one would hope that the author may return to look at this in more detail, as the question of why the Republican House leadership (in the first six years of the Obama administration, at least) seemingly abandoned the goal of legislating in exchange for party brand building is of great salience and interest.

A final, more general observation is that, as with so many studies such as this, the focus is entirely on the House of Representatives. There are reasons for this – the sheer number of legislators making for a better statistical sample, particularly – but by ignoring the Senate any analysis can only be half of the story.

That said, what this study does it does very well and makes for an important cautionary tale about how we should view and measure levels of partisanship in the United States Congress.