Consider three criminal cases.

No. 1: Christopher Newsom and his girlfriend, Channon Christian, both students at the University of Tennessee in Knoxville, were carjacked while on a dinner date in January, repeatedly raped (both of them), tortured, and killed. His burned body was found near a railroad track. Hers was stuffed into a trash can. Five suspects have been charged. The crimes were interracial.

No. 2: Three white Duke lacrosse players were accused in March 2006 of beating, kicking, choking, and gang-raping an African-American stripper, while pelting her with racial epithets, during a team party.

No. 3: Sam Hays bumped against Mike Martin in a crowded bar, spilling beer on Martin’s "gay pride" sweatshirt. Martin yelled, "You stupid bastard, I should kick your ass." Hays muttered, "You damned queer" and threw a punch, bloodying Martin’s lip.

Now the quiz.

Which of these would qualify as a federal case under a House-passed bill — widely acclaimed by editorial writers, liberal interest groups, law enforcement officials, and many others — expanding federal jurisdiction to prosecute "hate crimes"?

Bonus question: Why have the interracial rape-torture-murders in Knoxville been completely ignored by the same national media that clamor for more laws to stop hate crimes — the same media that erupted in a guilt-presuming feeding frenzy for months over the far less serious Duke lacrosse charges, which were full of glaring holes from the start and turned out to be fraudulent?

The answers.

The interracial Knoxville rape-murders would probably not qualify as hate crimes. The reason is that although the murderers were obviously full of hate, it cannot be proven that they hated their victims because of race. (Or so say police.)

Both the Duke lacrosse case and the (fictional) barroom scuffle, on the other hand, would probably be federally prosecutable under the bill that the House passed on May 3 by 237-180. This is because the angry words attributed to the accused could prove racist and homophobic motivations, respectively.

Do such distinctions make any sense? Not much, in my view.

The proposed Local Law Enforcement Hate Crimes Prevention Act would for the first time make it a federal crime to "willfully cause bodily injury" because of the victim’s "actual or perceived" sexual orientation, gender identity, gender, or disability. The bill would also expand federal jurisdiction over crimes motivated by race, color, national origin, or religion.

Sounds nice. But the pending bill — like most efforts to impose special penalties for bias-motivated crimes — strikes me as feel-good legislation likely to do more harm than good. The bill reaches only conduct that is already criminal under state law and thus serves no very important purpose; such proliferation of unnecessary new federal criminal laws diverts scarce resources from core federal functions such as fighting jihadist terrorism; and hate crime laws may even aggravate the biases that they are designed to counter by spreading the poison of identity politics. In addition, nothing in the Constitution empowers the federal government to prosecute many of the crimes that the bill is designed to cover.

As for the bonus question: The reason that the national media have ignored the Knoxville case is that the defendants are black and the victims were white. The media would also be uninterested if both the victims and the defendants were black. But had the victims been black and the accused white, the media would have erupted into the same politically correct sensationalism that characterized the Duke case. And many would have cited the case as proof that we need more hate crime laws.

The broader pattern is that the media, and many of the interest groups and academics who drive media coverage, habitually hype white-on-black crimes — and also gay-bashing violence — in keeping with their politically correct myth that straight white males are always victimizing racial minorities, women, and gays.

They also do their best to divert attention from horrible crimes involving African-American and gay defendants, and from the fact that "African-Americans — and particularly young black men — commit a dramatically disproportionate share of street crime in the United States," as Harvard law professor Randall Kennedy wrote in a 1999 New Republic article.

So it was that most of the media, the NAACP, and leftist Duke professors continued to smear the supposedly "privileged" Duke lacrosse players even in the face of ever-mounting evidence that the charges were false and the players innocent, as North Carolina Attorney General Roy Cooper declared last month.

And so it was that national media and other out-of-state outlets uttered not a peep this February about a new interracial-rape allegation at Duke with striking similarities to the lacrosse case. Again the accused was a Duke student. Again the locus was a drinking party in an off-campus house. Why the media silence? Because the accuser was white, the accused was black, and the house was rented by an African-American fraternity.

Other examples.

• The horrible murder in 1998 of James Byrd, an African-American, by three white supremacists who dragged him behind a truck for three miles near Jasper, Texas, became a national sensation and a rallying cry for more hate crimes legislation, even after two of the defendants got death sentences for plain old murder.

But the national media ignored the hauntingly similar murder in 2002, also near Jasper, of white hitchhiker Ken Tillery by three black men. They beat him, drove a car over him, and dragged him by the undercarriage for more than 20 feet. Ho-hum, said the media. Nor has this been treated as a hate crime. The supposed reason is that it involved a dispute over money. But had the races been reversed, I suspect, it would be high on the hate crime lobby’s list of examples.

• The 1998 murder of Matthew Shepard, a gay student at the University of Wyoming who was savagely beaten, lashed to a fence, and left to die near Laramie by two homophobic men, also became a media sensation and a rallying cry for extending hate crime laws to include those motivated by bias against gays.

But the media were far less interested when two gay men abducted and drugged 13-year-old Jesse Dirkhising in 1999, bound him with duct tape, gagged him with his own underwear, sodomized him with foreign objects, repeatedly raped him, gave him an enema of urine, and left him to die of suffocation. The Boston Globe and the Los Angeles Times failed to cover the case at the time, and The New York Times and many other media outlets have never mentioned it, a situation that gay journalist Andrew Sullivan (among others) has denounced as a double standard.

As John Leo recently wrote in The New York Sun, "The Shepard case was legitimately a huge story…. But there is something odd about the standard press defense [that] the Shepard story was news in a way that the Dirkhising story wasn’t because it ‘prompted debate on hate crimes and the degree to which there is still intolerance of gay people in this country,’ according to a Washington Post editor. This comes pretty close to advocacy…. Before long, more news consumers will conclude that even crime news is in effect being politicized. Is this any way to protect an industry in trouble?"

One reason for the double standards at work in these cases may be that many journalists, interest groups, and academics assume (incorrectly, in my view) that it would fan the flames of white racism and homophobia to paint a true picture of race and crime in America.

The deeper reason is that a true picture would undermine the same politically correct mythology that fuels the push for "hate crime" laws. This mythology also increases the large risk that such laws will be enforced very selectively, with evenhanded justice being eclipsed by politics, fanfare, and interest-group lobbying.

This risk may be the most important reason to oppose the House-passed bill.

The bill might be worthy of support if anyone could point to a single bias-motivated crime that it would have prevented. But nobody has. And such proposals have a lot more to do with political posturing than with ensuring that such crimes are adequately punished.

The Washington Post editorializes that we need this bill because hate crimes "terrorize whole communities." Bosh. It would be one thing if the KKK were on a violent rampage unchecked by local and state authorities. But that is not the case. The reality is that only a minuscule percentage of violent crimes are motivated by the targeted biases. And people murdered over money are just as dead as those murdered out of bias.

That’s why one leader said in 1993: "There is nothing more painful to me at this stage in my life than to walk down the street and hear footsteps and start thinking about robbery — then look around and see somebody white and feel relieved." The leader was Jesse Jackson. Passing another hate crime law would make him no safer.