When Washington first passed employment discrimination laws, Congress saw that anti-black discrimination was so widespread, so destructive and so intractable that the government was compelled to impose a remedy on private business. The question today is whether another intervention is warranted — or will it do more harm than good.

The Employment Non-Discrimination Act (ENDA) passed the Senate on Nov. 7 with supporters promising to end anti-gay discrimination in the workplace. The law may or may not do that — but it will certainly ban legitimate practices by private employers. Federal laws, after all, are not precision-guided weapons. They are blunt and they always inflict collateral damage.

If the Washington Examiner refused to hire a reporter simply because the reporter was gay, that would be wrong. But one can imagine cases in which an employer might justly place on employees conditions that are tied up with sexuality or gender identity.

Take a private boys’ school that publicly adheres to Christian teaching. The school is within its rights to prohibit its teachers from outwardly displaying a lifestyle that clashes with its moral teaching. If the teacher gets drunk publicly or regularly shows disrespect for clergy, it’s legitimate for the school to fire him — especially if these standards were made clear before hiring. (Schools run by churches would be exempt from ENDA, but many religious schools are independent from churches and would be covered.)

Some standards will relate to sexuality. Having a live-in girlfriend would clash with Christian teaching, and a school might not want a teacher who divorced and remarried without a Church-granted annulment of the first marriage.

In the same vein, the Catholic Church doesn't recognize same-sex marriages (and President Obama has repeatedly promised he wouldn't try to force the Church to do so). So does Congress have the right to bar an independent private school, publicly professing the Catholic faith, from firing a teacher for marrying someone of the same sex?

This hypothetical is a distinct issue from hiring or firing simply on the basis of sexual preference — it’s hiring and firing on the basis of public lifestyle. But it’s tied up enough with sexual preference that ENDA would affect it, thus impinging on legitimate practices by private employers.

Similarly, the bill bans discrimination based on “gender identity.” The idea is to protect people who suffer from what psychiatrists call “gender dysphoria” — the sense that your inner gender is somehow different from your biological gender. But what if your store clerk starts dressing like a woman simply out of anti-social rebellion? Has he now entered a protected class under ENDA?

A growing list of federally “protected classes” is dangerous. For one thing, hiring and employment practices may legitimately take into account race, gender, or sexuality in a way that’s hard to distinguish legally from simple bigotry. A newspaper might decide only a reporter of Chinese descent could effectively be its Chinatown correspondent. A women’s magazine might decide it needs a “Men’s Perspective” columnist.

As Congress and state governments have multiplied the list of protected classes, things have gotten messier. Is it really always wrong to try to hire a younger worker who can stick around for more years? Isn’t it legitimate for a law firm to assume a childless unmarried worker will be more available than a family man for the late nights a tough case might demand?

You may not agree with the boss’s decisions. You may think he’s cold-hearted. Similarly, you may find the sexual ethics of the Catholic Church impossibly stodgy.

But that doesn’t mean the federal government should always be involved. Not everything that’s wrong should be illegal. Sometimes these federal intrusions backfire: Studies have shown that employers are less likely to hire from protected classes, because firing that person is more legally perilous. Also, as Cato’s Walter Olson explains, expanding protected classes ties up the workplace with lawyers and litigation.

White racism in the 1960s was so widespread and so destructive that Congress decided it had to intervene. ENDA could remedy cases of unjust discrimination against gays — but in the process, it would make gays more expensive to hire, punish legitimate employer preferences and add to the stultifying accretion of government intrusion in private affairs.

Timothy P. Carney, The Washington Examiner's senior political columnist, can be contacted at tcarney@washingtonexaminer.com. His column appears Sunday and Wednesday on washingtonexaminer.com.