From Less Wrong, The Case Against Education: Splitting the Education Premium Pie and Considering IQ. In the aforementioned link, Caplan argues that IQ tests are a cheaper alterative to diplomas. Zvi counters that such tests are legally impermissible or too risky for employers:
Even if none of that is a concern, I’ll have to be continuously reassuring employees, applicants, investors and everyone else that this isn’t an issue. If everyone thinks it’s an issue, it’s a huge issue, even if I never get sued and no one ever threatens to sue me. And all of them will treat this as a huge negative signal, that I take stupid legal risks and make myself vulnerable, and that I waste my weirdness points, and that I care about all the wrong things. What other similar things am I doing? Will I still be in business in a few years? Should anyone rely on me for anything? Will others think the same ways, even if they shouldn’t, or think others will think in those ways?
I have observed that lay-commentators, on either side of the aisle, overestimate the legal jeopardy and rarity of cognitive screening in the workplace. They also overestimate the power of lawyers. Lawyers do not have magic powers to just shake-down people and companies for money. The legal process is long-drawn-out and expensive (if you think criminal cases are slow, civil cases are way worse). Cases are often dismissed, and civil lawyers do not want to waste time with cases they cannot win or settle, or suing defendants that are ‘judgement proof’.
Contrary to popular belief, IQ proxies are common and legally permissible despite Griggs. The Wonderlic, which is effectively an IQ test (good enough that Mensa is known to use it), is very common according to a Google search. A Google search also shows zero results of any employer being sued, let alone successfully sued , for administering an IQ-like proxy such as the Wonderlic (except for results about Griggs and debate pertaining to Griggs, not actual non-Griggs cases).
The Wonderlic website claims to have a 100% percent success rate against lawsuits when the test is properly administered. It’s worth mentioning again that disparate impact cases face two big hurdles: proving extant disparate impact, and then proving that the test was ill-applied or inapplicable to the job
The NFL has been using the Wonderlic for decades, and hasn’t been sued yet despite African Americans consistently scoring worse on it, and the dubious applicability to gridiron football. In 2021, the NFL stopped administering the tests but for reasons unrelated to litigation, although individuals teams still have discretion to use it.
If I give an IQ test, it’ll be awkward. Applicants will see me test them and think it is weird, turning them off. Employees will see me doing it, and think it’s weird and uncaring and potentially legally dangerous. Everyone around could sue me, or more importantly could threaten to sue me, or perhaps even more importantly everyone knows that everyone is worried that anyone could implicitly threaten to sue me. So now I’m afraid of publicity, I’m afraid of anyone getting mad and wanting to go after me, I’m afraid of my own shadow. Any reporter who gets a whiff of this might shift their story to my terrible practices.
As for weirdness or awkwardness, again, this is not an issue. Because such tests are administered at the pre-employment stage, employees will not see it, nor do they care. Applicants will have to take the test in a carefully proctored setting, not a social one, to prevent cheating. Applicants do not care either; the worst that can happen is they vent online (like the above Reddit search shows), which has no affect on anything. No lawyer will take the case, because such tests are legal.
Regarding bad publicity, similar to above, zero Google search results. Sure, some columnists may complain about the NFL using an ‘antiquated test’ that is of allegedly little predictive value, but this is not the same as the WSJ or the NYTs dropping a front-page bombshell.
 There was a second, less famous case, EEOC v. Atlas Paper Box Co, 1987, which was entered in favor of the defendant:
Accordingly, the Court finds that the plaintiff has failed to carry its burden of proof on either its disparate treatment or disparate impact theory of liability. Judgment will enter in favor of the defendant Atlas Paper Box Company.
But there have been instances of candidates being excluded for scoring too high on the Wonderlic, notably Robert Jordan, who in 1997 applied to become a police officer but was rejected for his high score, which after he sued, in 2000 was held up by 2nd U.S. Circuit Court of Appeals in New York as legal.
Edit: there was one case by the EEOC in 1992 against Ford, EEOC v. Ford Motor Co. and United Automobile Workers of America, which led to a settlement. But it did not involve the Wonderlic though (Ford used a different test, called the Apprenticeship Training Selection System (ATSS)), and one successful case over a 30-year period is a pretty low success rate.