On Friday, three groups sued San Francisco to overturn a terrible new city ordinance that restricts the free-speech rights of those who make and market sweetened drinks like soda. The plaintiffs, the American Beverage Association, California Retailers Association, and California State Outdoor Advertising Association, are seeking immediate injunctive relief—to prevent the law from taking effect—and have asked the District Court to overturn the law.

The ordinance, which I discussed at various outlets shortly after it was proposed, requires mandatory warning labels to appear on all soda ads in the city, including those on billboards. The law requires that at least 20 percent of each ad's space read as follows: "WARNING: Drinking beverages with added sugar(s) contributes to obesity, diabetes and tooth decay."

That warning is shaky at best. "Mandatory 'added sugar' labeling may violate the First Amendment," I wrote here in March, before the San Francisco law had been proposed. "Use of the term 'added sugar' is misleading, as it creates a deceptive health halo around products like orange juice and apple juice, which are high in naturally occurring sugar but contain no added sugar."

While the ordinance compels that warning, it also contains a host of equally shocking restrictions on free speech. For example, the law would prohibit soda makers from identifying the products they sell while protesting against the law on public space. It bars ads advertising soda, Frappuccinos, or some Jamba juices on public property—including buses, parks, and bus stops—but allows, notably, ads attacking such drinks. It also engages in other forms of viewpoint discrimination. It contains vague and undefined terms, including "producing sugar-sweetened beverages." Those restrictions, the compelled speech, and other clear violations of bedrock First Amendment principles forced the American Beverage Association and its fellow plaintiffs to sue.

This is a case about ensuring that government can't restrict speech simply because it doesn't like that speech, and can't force a company to warn consumers off of its products without good reason. Such reasons don't exist in this case.

While the case is an important one for protecting our First Amendment rights, it's also an important case for upholding principles of food freedom. After all, what good is the right to produce and sell legal food if you can't also market the food to consumers? Clearly, this is a bad law that restricts the rights of soda companies and consumers.

Historically, courts have found the First Amendment prohibits the government from restricting free speech because it doesn't like the speaker's message. Courts have also struck down laws in cases, as here, where the government compels a speaker to substitute the words they would have said with ones the government forces upon the speaker.

Both types of First Amendment violations exist here. This should be an open-and-shut case. I think San Francisco should save its taxpayers money and repeal the law, rather than defend it in court.

Food makers have a First Amendment right to market a legal food product to potential consumers. Consumers have a right to hear that message. No government has the power to restrict those rights.

I've previously defended the First Amendment rights of PETA and Dr. Oz. Needless to say, those who make and market soda must enjoy those same First Amendment rights.

"The First Amendment violation here is direct and flagrant," the lawsuit notes. It also rightly describes these bedrock principles as part of "hornbook law," a reference to the fact almost any law student could, thumbing through their legal hornbook, likely describe how San Francisco's ban impermissibly restricts speech that is protected by the First Amendment.

"The Ordinance is precisely the kind of 'paternalistic' speech regulation that the courts have long condemned," the suit notes, calling the law "starkly incompatible with the First Amendment."

One thing I'll be watching closely is how the District Court rules on the question of whether an added-sugar warning is misleading. Your "body doesn't distinguish between natural or added sugars," reads a Harvard School of Public Health publication.

Despite that fact, the FDA has moved to require food labels list both total sugar (which is reasonable) and added sugar (which is, again, misleading). This case could find a federal court not only overturning San Francisco's unconstitutional free-speech ban but also siding against the flimsy arguments that compelled the FDA to propose its added-sugar label. Wouldn't that be sweet?