In the 10th edition of Systema Naturae, published in 1758, Carl Linnaeus, the king of the classifying sciences, declared that “by good right and just title, according to the law of nature,” a whale was a mammal and not a fish. Although they reside in the ocean, Linnaeus observed, whales breathe through lungs, are warm-blooded, give birth to live young, and suckle their offspring. Systematic taxonomists fell into line and by the end of the century the nonfish whale had been incorporated into the naturalist’s world.

For most people, however, a whale remained a fish. Ishmael would speak for them at midcentury in Moby Dick, as he dismissed learned commentary on cetology, called on Jonah and seamen with callused hands for support and declared the whale a spouting fish with a horizontal tail. In 1818, the old salts had their day in Mayor’s Court in Manhattan. Maurice v. Judd pivoted on whether whale oil was fish oil and therefore subject to New York State inspection. Plaintiff James Maurice—the state inspector—argued that whale oil was fish oil; defendant Samuel Judd—the candle maker and oil merchant—begged to differ. According to Princeton historian D. Graham Burnett, the trial showcased a confrontation between folk taxonomies, buttressed by the Bible, and scientific expertise—over nothing less than the order of nature.

In Trying Leviathan, Mr. Burnett brilliantly deconstructs the controversy. To tease out the “many strands of argument,” he uses four “actor’s categories”—philosopher-naturalists; fishermen-whalers; merchants and manufacturers; and “ordinary” New Yorkers, who had no direct stake in the outcome. At once bewitching and bookish, with a Dickensian cast of characters (including a sea captain named Preserved Fish), Trying Leviathan bristles with insights about the relationships between popular belief, democracy, science and the law that resonate with contemporary controversies over Darwinism and intelligent design. Mr. Burnett brings new meaning to Herman Melville’s aphorism: “When Leviathan is the text, the case is altered.”

Arguing that the early 19th century was not a taxonomic calm before the Darwinian storm, Mr. Burnett demonstrates that the authority of science was uncertain, fragmented and challenged. Resistance was especially intense when naturalists used comparative anatomy against outward appearances and common-sense classifications.

William Sampson, the lawyer representing inspector James Maurice, carved up the contested terrain with sophisticated and sophistical arguments. Lampooning scientists who arrogated to themselves “the sole privilege of new-creating and nicknaming God’s creatures,” Sampson attacked the “forced and incongruous groupings of animals every way dissimilar, in the same order.” Because whales lacked hair and feet and lived in the water, he pointed out, some naturalists refused to classify them as mammals, retaining the traditional tripartite categories of creatures who fly, swim and creep. Sampson used the openness of science to new hypotheses to discredit science. The “perpetual pageant of rearrangement,” he suggested, rendered classification little more than an ever-changing game of king of the hill.

Sampson and his co-counsel, John Anthon, also took naturalists to task for elevating brutes—whales, dolphins and porpoises—to kinship with human beings. At the very moment when New Yorkers were debating whether to extend the franchise to African-Americans, Mr. Burnett observes, Anthon played the race card.

THE STAR WITNESS for Judd, arguing the case for whale-as-mammal, was the eminent physician, politician and professor of natural history, Samuel Latham Mitchill. John Anthon harpooned him with a pointed analogy aimed straight at racial prejudice. Would Mitchill also claim that an “orang outang” was a freeman, entitled to vote? “He breathes the vital air, the Doctor might say, through lungs; he moves erect, & has warm blood; the female brings forth her young alive, and rears the bantling at her breast.” Anthon could confidently predict the ordinary New Yorker’s bemused response: “All this indeed is very strange and curious, but still, Doctor, it is a monkey in common acceptation, however naturalists may choose to hail and class him a brother.”

Most tellingly, the lawyers for the plaintiff emphasized that statutes are designed to regulate the conduct of the whole community. In framing and interpreting them, legislators and jurors relied on popular knowledge (of the whale-is-fish variety). And so they should. Likening naturalists to the leviathans they anatomized, Sampson thundered that the citizens of a democracy should not be “spoon-fed by doctors of medicine, with ill-concocted Greek, such as Greek babies would spit out.”

Samuel Judd never stood a chance of proving that a whale is not a fish. As Sampson skewered the scientists, Judd’s lawyers shifted their ground: Even if a whale is a fish, they argued, whale and fish oil are no more the same than sugar and molasses. Customers know the difference—and don’t give a fig about taxonomy. They also asked the jury to ignore the contemptuous epithets directed against their witnesses merely because they were Massachusetts men—and not New Yorkers.

It was too little, too late. After deliberating for 15 minutes, the jury announced a verdict for the plaintiff. “Pray sir, how goes it with whale oil now?” the New York Evening Post asked. “Is it oil of fish, or of flesh, or of red herring?” Within a month, the New York State Legislature essentially overturned the verdict by exempting whale oil from inspection—in the eyes of the law, the whale would no longer count as a fish.

But as Mr. Burnett notes in his conclusion, the courtroom drama staged by Sampson and Anthon—“the one that pitches society against science (or vice versa)”—is played out again and again, throughout our history, as laymen and experts separate and come together in disorderly and disturbing debates about the order of nature.

Glenn C. Altschuler is the Thomas and Dorothy Litwin Professor of American Studies at Cornell University. He can be reached at books@observer.com.

"Just go in," a friend once advised when I got called for jury duty, "and say, 'I cannot be rational.' Say, 'I hate criminals, and if they're arrested they're guilty as far as I'm concerned.' And they'll let you go." Most upper-middle-class people pull stunts like this. D. Graham Burnett notes in his account of jury service that 80 percent of his own juror pool asked to be excused when, during voir dire, the judge mentioned sequestration. Roughly half of them waved their hands when the clerk asked-in English-if they were unable to understand English.

Mr. Burnett, a Princeton University historian of science, refused to crap out on his civic duty, even though his profession is one in which concepts like "reasonable doubt" routinely get shot full of epistemological holes. He wound up as the foreman of a jury sitting on a murder trial. Several days of testimony and four days of sequestration (which he describes as "the most intense sixty-six hours of my life") turned him into a sobbing wreck with some strongly held ideas about the on-the-ground workings of our justice system. He lays them out in a slight but snappy book called A Trial by Jury , the gist of which he squeezed into a recent New York Times Magazine cover story.

In August 1998, a gay African-American man was found dead in his West Village apartment with two dozen stab wounds to his chest and back. (Mr. Burnett, who has changed the names of all the case's principals, calls this man "Randolph Cuffee.") The NYPD did what it always does after a stabbing death-it canvassed the city's emergency rooms for patients with hand wounds. They found "Monte Milcray," a young Bronx man who'd nearly severed one of his fingers. His alibi stank. Milcray, who was black, claimed to have used a knife to fend off a gang of white racists during a chase that covered 25 city blocks and left him suspiciously close to Cuffee's apartment. When police tested the overalls Milcray had been wearing, they discovered a mix of his and Cuffee's blood.

So Milcray changed his story to the one he'd more or less stick with for the rest of the trial. He claimed a woman in Union Square had called him "sexy" and invited him to her apartment. When the "woman" disrobed, there was a Crying Game moment. "What the fuck is this?" Milcray said. Cuffee allegedly replied, "Once it gets in, it's not gonna hurt"-and was doing his level best to rape Milcray when the latter reached for the blade he kept strapped to his ankle. Milcray, who was engaged to be married, backtracked on one aspect of the story: He admitted that he'd met Cuffee not on the street but on a dirty-talk phone line. Phone records backed him up; Cuffee was shown in testimony to have run "a small gay escort service." Prosecution and defense differed over whether he himself had ever solicited clients in drag.

Mr. Burnett and his fellow jurors were sent off either to convict Milcray for second-degree murder or to acquit him on grounds of self-defense. There was no middle ground: Either Cuffee had been a rapist or Milcray was a liar. The risk of a not-guilty verdict was that a cold-blooded murderer would be set free, rewarded for a homophobic tall tale. The risk of a guilty verdict was that a law-abiding man would be robbed of his liberty simply for having defended himself against a violent pervert.

Mr. Burnett didn't have much to work with: The other 11 jurors included one egotistical television addict who used deliberation time to discuss how Jews call all the shots in the Dominican Republic, and who was under the impression that the defendant would serve a long jail sentence no matter what verdict they reached; one woman who argued for a compromise verdict because she had a friend who was raped in police custody in Turkey; one interior decorator who argued for a more "sensual" approach to the law; and one "emotionally volatile" control freak who had to be hospitalized when her meds ran out.

To many of his fellow jurors, Mr. Burnett was no great shakes, either. He looked like a snot, reading Wallace Stevens on breaks and taking his notes with a fountain pen that "contained a foppish, tobacco-colored ink." He was an inveterate food sissy, eating only the fruits and nuts and breads he'd stuffed into his knapsack and barely touching the meals served at the hotels near Kennedy and La Guardia where the jurors were bused for the night. And he had, as he himself realizes, a tendency to bloviate and to condescend. "In different circumstances," he wrote in his notebook, "I can imagine having a certain kind of conversation that could bring me around to reject the justification of self-defense. But there are some jurors here who are such idiots, so thoroughly oblivious to good judgment, or so thick (regardless of their intentions), that it seems improper to aid them in depriving a man of his liberty." He began deliberations hoping for a hung jury.

Many readers will be inclined to compare Mr. Burnett's book with that other brief examination of courtroom "truth," Janet Malcolm's The Crime of Sheila McGough (1999). They'll find a paradox. Ms. Malcolm, a more "literary" interpreter of legal narratives, assumes jurors are intoxicated by logic: "Trials are won by attorneys whose stories fit," she writes, "and lost by those whose stories are like the shapeless housecoat that truth, in her disdain for appearances, has chosen as her uniform."

But as a juror, the presumably more "scientific" Mr. Burnett was drawn to illogic and loose ends. The great argument for the truth of Milcray's account, he thought, was its sloppiness. According to Milcray, Cuffee didn't threaten him and didn't even have a weapon. "If he had invented this tale of attempted anal sodomy in an effort to dodge prosecution for a cold-blooded murder, why didn't he have the good sense to embroider his account of the attack in order to make it more obviously life-threatening?" Mr. Burnett asks. "Milcray's story was weak, weaker than it needed to be, weaker than a calculated lie would have been. It was, in the end, improbable enough to leave the distinct impression of truth."

Still, it was not just truth's shapeless housecoat that made Mr. Burnett's fellow jurors vote unanimously for acquittal on the fourth morning of deliberations; most of them still suspected that Milcray had done something wrong. It was, rather, the annoying experience of sequestration that showed them the rationale behind the notion of "reasonable doubt." They had been put off by the cops who "exuded a palpable sense of armed delight" as the courtroom cleared; by the overzealous prosecutor, whose idea of a question was: "And didn't you then-like this!-stab him? And then-again!-like this? As he tried to crawl away? And-again!"; and by the blowhard judge, who dressed down Mr. Burnett for stretching his legs and threatened another juror with contempt of court for not looking at him while he was speaking, before concluding his performance with a sneering lecture about how jury duty "was by no means a service comparable in scope to that which had been demanded of the men of his generation."

Doing his duty taught Mr. Burnett a sobering lesson: "[T]he burden of proof was so high exactly because the state was so powerful ," he writes. "[T]he state could take control of your person, it could refuse to let you go home, it could send men with guns to watch you take a piss, it could deny you access to a lawyer, it could embarrass you in public and force you to reply meekly, it could, ultimately, send you to jail-all this, apparently, without even accusing you of a crime."

And it could withhold evidence. It's easy enough to find the actual case Mr. Burnett is describing-the killing of the 36-year-old Fitzroy Green by 21-year-old computer programmer Eric Carolina in the wee hours of Aug. 18, 1998. The Carolina/Milcray story is backed by plenty of evidence that the jurors were not permitted to hear. Green/Cuffee was indeed a transvestite prostitute-and with a record of violence. In 1997, according to the New York Post , Green "was accused of cutting off a john's pinky finger after the customer got angry when he discovered Green was only masquerading as a woman."

It was, in short, a narrow escape from a miscarriage of justice. It is to Mr. Burnett's credit that he leaves out this clarifying material. The reader passes through the book blinkered in the same way a jury is blinkered-and finishes it with gratitude to Graham Burnett for having brought his fellow panelists around to his own anti-authoritarian intuitions.

Christopher Caldwell is senior writer at the Weekly Standard.