Determining the limits of moral turpitude encounters line-drawing problems similar to determining the constitutional definition of obscenity. Vagueness threatens both definitional enterprises. A statute is vague when it "fails to give a person of ordinary intelligence fair notice that his contemplated conduct is forbidden by the statute." (United States v. Hariss (1954) 347 U.S. 612, 617.) An ineliminable vagueness may infect pornography regulation, as over decades of deliberation, no jurist has proposed an adequate definition. As for moral turpitude, the California courts have always admitted they cannot define the term. Is "moral turpitude" vague? While the problems of defining obscenity have chagrined our highest court's justices, the courts appear unconcerned about moral turpitude's conceptual reliability.
Justice Brennan set out the modern framework for constitutional regulation of pornography in Roth v. United States (1957) 354 U.S. 476. The different lines of interpretation were also set out in that case or subsequent ones, with alignments sometimes unexpected from the justices’ broader ideological commitments. Chief Justice Warren took a moderately conservative position on this issue, arguing in Jacobellis v. State of Ohio (1964) 378 U.S. 184, 192, for using local rather than national standards. Justice Brennan's lead opinion, in both Roth and Jacobellis, is itself moderate at most. Justices Black and Douglas opposed all censorship with an argument impugned only by the country's historical acceptance of anti-obscenity laws, adopted by all states. Brennan had admitted that the purpose of anti-obscenity laws was to avoid instigating impure thoughts. With this concession, how could the defenders of censorship claim obscenity was unprotected because of its lack of social value? Indifference to thought crimes is the foundation of free speech, and the state's abstention from evaluating speech's social value, the right's core. Justice Stewart had stated what many think emblematic of the pornography debate, when, in his concurring opinion in Jacobellis, he wrote, "I know it when I see it." This position comes rather close to the way the California courts identify moral turpitude. But like quotes of the Oliver Wendell Holmes Jr.'s remark about free speech not including the right to yell "fire" in a crowded theater, Stewart's remark is usually quoted out of context. Holmes had actually proscribed yelling fire in a crowded theater only when no fire existed. Similarly, Stewart had said, "But I know it [hard core pornography] when I see it, and the motion picture involved in this case is not that." Stewart's remarks defended his opinion that the movie was not obscene, and the out-of-context quote is misleading.
If Stewart's misunderstood comment is the most famous part of the pornography debate, the evolution of Justice Brennan's position is the most interesting. Justice Brennan ultimately abandoned the Roth framework. In dissent in Paris Adult Theatre I v. Slaton (1973) 413 U.S. 49, he assumed a stance close to Black, Douglas, and Stewart and analyzed the failure of the attempts at definition. Black and Douglas — and more subtly, Stewart — had argued that obscenity laws were capricious because obscenity still begged for definition. Brennan, unlike Justices Black and Douglas, still believed in principle that the state's police power included the right to prohibit obscenity, but Brennan now believed objective definition was impossible. Without objective definition, prohibition was unconstitutional. In his Paris Adult Theatre dissent, Justice Brennan considered how possible changes in constitutional anti-obscenity standards would affect the laws' defects and viability. The first of Brennan's thought experiments answers why vagueness controversy does not besiege the moral turpitude standard. Brennan's analysis shows that the definition of obscenity could achieve adequate precision only by resolving every doubt in favor of the state's right to censor.
This correlation between precision and scope determined the evolution of the moral turpitude standard. Consider as example, willful failure to pay income taxes. Does it constitute moral turpitude, warranting attorney discipline? The California Supreme Court confronted this issue for the first time in In re Fahey (1973) 8 Cal.3d 842. Since Fahey had not lied or intended to defraud — other matters and personal disorganization harried him — the Supreme Court unanimously decided to dismiss the case. The court also based dismissal on the further holding that attorneys should face discipline only for acts of moral turpitude, interpreted to reflect characterological unsuitability for law practice. Five years later, the California Supreme Court unanimously decided to discipline an attorney for a similar failure to pay income taxes. (See In re Rohan (1978) 21 Cal.3d 195.) The lead opinion justified discipline by renouncing moral turpitude as the sole basis for discipline. Rohan was not culpable for moral turpitude, but his crime warranted discipline for other reasons. A concurring opinion by Tobriner and Mosk opposed abandoning the exclusive moral-turpitude standard for discipline, yet still favored imposing discipline on Rohan because these concurring jurists understood willful failure to pay income taxes to involve moral turpitude. Although differing on criteria, the justices closely agreed on the level of discipline, which involved a 60-day actual suspension.
Brennan had predicted a clear definition of "obscenity" would cost an increase in its reach. This extension occurred in First Amendment obscenity cases, when the Burger court moved the standard from the complete absence of redeeming social value to lacking serious value and from a national standard of community opinion to local standards. The concept of moral turpitude has undergone the same change, both by broadening moral turpitude's definition and supplementing the standard to broaden discipline's sweep. The courts have avoided vagueness in the moral-turpitude standard by broadening the concept or its surrogate to include borderline cases.