At some point in your life, you’ve probably received a call where the name and/or number that showed up on caller ID was not the actual name/number of the caller. It’s known as spoofing, and many people assume it’s illegal. Those people would be wrong.

The L.A. Times’ David Lazarus points out that spoofing is illegal in cases where it’s used to commit fraud or otherwise perpetrate a crime, but that is something that is proven after the fact. Thus, you need to show that a telemarketer that hides behind a spoofed phone number is also trying to defraud the recipients of the calls.

As recently as last year the Fifth Circuit Court of Appeals upheld [PDF] the legality of “non-harmful spoofing,” when it overturned a Mississippi state law against spoofing.

In that case, a New Jersey company that offers spoofing technology had challenged the state legislation, saying it undercut the federal Truth in Caller ID Act, which allows for spoofing in cases where no harm is intended. The appeals panel gave the example of a domestic-violence victim trying to hide her whereabouts as a justifiable use of spoofing.

Of course, the problem is that it looks like most spoofing is being done, not by individual consumers looking to protect their privacy, but by companies with questionable motives attempting to appear more legitimate. But since the law presumes that spoofed calls are not in themselves harmful, the practice continues.

And it’s not just a matter of being annoyed by telemarketers. Ask the man who recently began receiving angry phone calls from strangers because some telemarketing company selected his number as the one that showed up when cold-calling consumers.

“They all saw my number on their caller ID screen,” he tells Lazarus. “They were upset that I seemed to have called them and then hung up just as they picked up the phone, like I was a robo-caller.”

He contacted AT&T, which couldn’t really do anything about it. His complaint to the FCC just pointed him back to that lovely Truth in Caller ID Act, which said the calls were legal so long as the telemarketer isn’t attempting to harm the recipient.

Of course, the younger generation of smartphone users don’t even use the “phone” portion of their devices, and it’s more difficult to sell scammy auto warranties via text, so maybe spoofing will soon become a relic of a day when human beings actually talked to each other on the phone.

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