When I was five or so, I was watching some movie for grownups, which mostly bored me. But my ears pricked up when someone was talking about getting married, and saying that they could go get the blood test right away.
Blood test? You had to get a thumb stick to get married? I turned to my mother, and she solemnly informed me that this was so. I was distinctly disappointed. I hated blood tests. I’d had enough already. If I was going to get blood drawn I just was not going to get married. But then, I thought, I guess that was the test: grownups don’t mind blood tests, and if you’re not grown up enough to get blood drawn you’re not old enough to get married.
It has come to my attention that people no longer remember that this was once a small tradition in American marriage. According to this site, only Montana now requires it. The blood test, although invasive and faintly eugenic, was well intended. Before the advent of antibiotics, syphilis might percolate quietly, asymptomatically inside someone for years. Before the advent of the sexual revolution, when young ladies were forbidden to speak frankly or listen to frankness, men might go out to visit women who were not young ladies and bring home a case of syphilis to their innocent brides, resulting in illness and death for mother and child.
This is the sort of narrative that would tug the heartstrings of early 20th-century legislators. In a time before American women had much power or authority in sexual matters, perhaps the laws did save a few of them. But by and large, the test was not cost-effective; it found very few positive results. Syphilis itself could be cured by antibiotic treatments after World War II, and no longer had the same power to destroy lives.
STD testing and genetic testing are certainly a good idea for couples, but state law has mainly lost interest in mandating these things. You no longer have to be grown up enough to get stuck with a needle in order to get married.