In his book, Tom Campbell, a former five-term member of Congress, argues that we ought to focus on the “comparative advantage” of each branch because by doing so, we improve the operation of American government. “The thesis of this text is that each branch has inherent advantages: for each branch not to use its advantage and, worse, to allow another branch to encroach upon it dulls the mechanisms of governmental action” (p. 58). After highlighting his case studies in his introduction, in Part One Campbell discusses the advantages of each branch, the rules of the legislative process, the process of statutory construction by courts, and the judicial practice of following precedent. In Part Two he presents 10 case studies, which exemplify his thesis.

Campbell begins his account of the “comparative advantages” of each branch with the judiciary. Courts “can … develop rules of evidence and presumptions that yield orderly resolution of disputes,” which include the burden of proof. A judicial trial also provides for the development of procedural fairness to balance private claims that legislative hearings cannot duplicate (p. 19). When constitutional rights are involved, the judicial branch resists popular pressure to disregard the rights better than the political branches do. Campbell criticizes the judicial branch's reliance on precedent (stare decisis), which he distinguishes from a lower court's following the decisions of a higher court. He claims that the Supreme Court rarely decides a case on these grounds. This includes Planned Parenthood v. Casey, because “nowhere in her opinion does Justice O'Connor state her belief that, had she to rule on Roe v. Wade, she would have ruled with the dissent” (p. 78). But that opinion (a joint opinion of Justices Sandra Day O'Connor, Anthony Kennedy, and David Souter) does state that “the reservations any of us may have in reaffirming the central holding of Roe are outweighed by the explication of individual liberty we have given combined with the force of stare decisis” (505 U.S. 833, 853). Campbell would probably reply that this passage illustrates a rhetorical reliance on precedent and nothing more (p. 78).

The author regards the requirement that courts decide particular cases “by announcing a general principle” as another disadvantage (p. 21). He refers to his later discussion of the Fiesta Bowl, where a broad judicial decision, which involved cutting off federal funds to academic institutions, yielded bad policy results that Congress had to remedy (Chapter 9). A constitutional amendment can address a specific problem more narrowly than a judicial decision. Campbell uses flag burning as his example. After the Court invalidated a state law protecting the flag, Congress considered how to write legislation to get around the decision. He criticizes the Court for including language (perhaps to assure the vote of the late Justice Harry Blackmun) that encouraged Congress to try what turned out to be futile, as the Court invalidated the federal law by the same five-to-four vote. Without taking a stand on the merits, Campbell argues that a constitutional amendment would have been the more appropriate response; it would have trumped the Court on this particular issue only. Although the constitutional amendment is an important check on the judiciary, and it may be more targeted than a Supreme Court decision, he does not consider the likely unsettling effect of reliance on constitutional amendment to overturn unpopular judicial decisions.

Because the judiciary must wait to respond to the particulars of a case, Campbell favors private rights of action, and he favors standing for members of Congress, so long as they have demonstrated a clear legislative interest in the issue (see pp. 197–206). He cites the Second Amendment to illustrate that the judicial branch is under no obligation to act. Here, as with stare decisis, Campbell thinks the Supreme Court should change its behavior (Chapter 13). Finally, he cites the judiciary's limited ability to ascertain facts “not of the kind presented as evidence in trials” (p. 22). He criticizes that part of the Court's treatment of the exclusionary rule that tries to justify first the rule and then the exceptions on the basis of predictions concerning deterrence. Instead, he offers a different approach; a principled approach to rights would support the exclusionary rule, and the exceptions to it would grow out of a waiver of the right against self-incrimination (see Chapter 7).

Among the three branches, the legislative branch's chief advantage resides in its power to “order any kind of study it needs.” The legislature is thus “the master of words,” and it “can write the laws” (pp. 22–23). The legislative branch best balances interests. Here (p. 24) and elsewhere (pp. 101 and 112) Campbell argues that courts are best at protecting rights, whereas legislatures are best at treating interests. This is an important distinction for Campbell and it probably has merits in some cases. But in others, such as cases where the courts exercise “strict scrutiny,” fundamental rights must be balanced against compelling state interests.

“The greatest advantage of the executive branch,” according to Campbell, “is its flexibility. It can respond to a problem by instructing an agency to deal with it. It can order a rule to be promulgated … much faster than it takes for a typical law to be pass.” Moreover, prosecutorial discretion “can ameliorate the potential injustice … from the application of a harsh rule to specific conduct” (p. 25). On the other hand, in the absence of a private right of action, the executive branch can nullify the intent of the legislature by failing to bring an enforcement action. Hence, Campbell favors legislative enactment of private rights of action, as he favors standing for legislators after they demonstrate legislative support for their position. He also argues that “[t]he executive's power to present the other branches with a fait accompli is another problem” (p. 26). Unity in the executive has the advantage of speed and resolve and the disadvantage of “frequency and gravity of error,” which, however, it can correct (p. 26).

In Separation of Powers in Practice, Campbell's focus has the virtue of getting lawyers and judges to take the other two branches of government seriously. His chapter on the rules of the legislative process reveals how lawmakers' voting records need to be studied carefully, and his chapter on statutory construction argues that “subsequent legislative action, inaction, or commentary” (p. 55) does not say much about legislative intent. He also demonstrates to political officials and critics of the judiciary the important role that courts play in upholding the Constitution.