* Marrs Mc Lean Professor in Law, University of Texas School of Law. For valuable comments and conversations, we are grateful to Bruce Ackerman, Jack Balkin, Joseph Blocher, Curt Bradley, Jessica Bulman-Pozen, Josh Chafetz, Guy Charles, Kimberlé Crenshaw, Walter Dellinger, Ryan Doerfler, Nita Farahany, Cary Franklin, Jonah Gelbach, Jamal Greene, Adam Katz, Jeremy Kessler, Marty Lederman, Maggie Mc Kinley, Gillian Metzger, Caleb Nelson, Eric Posner, Jed Purdy, Kelsey Ruescher, David Schleicher, Peter Schuck, Neil Siegel, David Super, Eric Talley, Mark Tushnet, and workshop participants at Columbia, Duke, Harvard, and Penn law schools. Research Serv., IN10469, Supreme Court Vacancies that Arose During One Presidency and Were Filled During a Different Presidency 1 (2016).Since at least the mid-1990s, Republican officeholders have been more likely than their Democratic counterparts to push the constitutional envelope, straining unwritten norms of governance or disrupting established constitutional understandings. But contrary to the apparent assumption of some legal scholars, they have not done so with the same frequency or intensity.After defining constitutional hardball and defending this descriptive claim, this Essay offers several overlapping explanations.Finally, and more tentatively, this Essay looks to the future.In reaction to President Trump, congressional Democrats have begun to play constitutional hardball more aggressively. Absent a fundamental political realignment, we submit that there are good structural and ideological reasons to expect the two parties to revert to the asymmetric pattern of the past twenty-five years.This episode is an interesting if imperfect precursor of the phenomenon this Essay will discuss.The political factions in 1968 did not match up neatly with the parties.This might seem like a reckless prediction to make at a moment when so much is in flux. Although Tushnet allows for the possibility of judicial constitutional hardball, his account focuses on legislative and executive actors, and the most straightforward cases of hardball often occur in legislatures.But this Essay will document a number of longer-term dynamics that seem poised to perpetuate the divide. Legislative bodies teem with rules and norms, not expressly required by constitution or statute, that govern the interactions among political blocs within the institution.As Professors Robin Bradley Kar and Jason Mazzone have detailed, the Senate had never before “deliberately transfer[red] one President’s Supreme Court appointment powers to an unknown successor” in the absence of “contemporaneous questions about the status of the nominating President as the most recently elected President.” Robin Bradley Kar & Jason Mazzone, The Garland Affair: What History and the Constitution Say About President Obama’s Powers to Appoint a Replacement for Justice Scalia, 91 N. For a quarter of a century, Republican officials have been more willing than Democratic officials to play constitutional hardball—not only or primarily on judicial nominations but across a range of spheres.Democrats have also availed themselves of hardball throughout this period, but not with the same frequency or intensity.