In the world of skin care and makeup, there are products that those in the know consider best in class. Sunday Riley’s Good Genes acid serum is one. La Mer’s moisturizer is another. And Skinceuticals’ CE Ferulic — a glass dropper bottle full of yellow, watery antioxidants whose scent has been likened to hot dog water — is one of the most prized, if all the dermatologist recommendations and gushing testimonials are to be believed.

But now L’Oréal, the multinational beauty conglomerate that owns the Skinceuticals brand, is suing an indie competitor, alleging patent infringement. The product in question is Drunk Elephant’s C-Firma serum, which has been widely hailed by skincare fans and publications as a cheaper alternative to Skinceuticals’ cult-favorite vitamin C serum. Vitamin C serums can theoretically even out skin tone and prevent sun damage and wrinkles.

Faced with a crowded and imitative market, beauty obsessives have created a culture, discussed on forums and in Instagram posts, around the search for affordable alternatives to their favorite products. Hunting for these so-called “dupes” is entertaining but also potentially economical. At $80 for one ounce, Drunk Elephant’s serum is half the price of Skinceuticals CE Ferulic, which costs an eye-watering $166 for the same volume.

Drunk Elephant is one of the biggest success stories in skin care, during a time when skin care sales in general are booming and skin care itself has become a crucial part of “self-care,” garnering national attention. Its products are best-sellers at Sephora, and the brand expects to exceed $100 million in sales this year, according to Business of Fashion.

The company recently expanded to the UK and will soon expand to Asia. Its brightly neon-colored bottles and “clean” ingredient messaging have made a winning combination. Forbes has estimated that the brand has received about $25 million in investments, including from Man Repeller blogger Leandra Medine.

So, Drunk Elephant is big enough that it is likely biting into Skinceuticals’ sales. This suit could have wider implications in the beauty industry, which is rife with copycat products thanks to a robust cottage industry of dupes.

Dupe culture is prevalent in the beauty industry

Some of the best-loved products in the beauty industry are also incredibly expensive. As such, there is an enthusiastic group of superfans who will test (or “swatch”) products like eye shadow and lipstick to find cheaper versions that are good matches for the pricier originals. They pop up via Instagram pages like DupeThat (which has more than 1 million followers) and popular makeup review blogs like Temptalia, which has a whole section devoted to dupes.

Since skin care isn’t as visual as makeup, and formulas and ingredients matter more, dupe-hunting in the category happens more organically in forums like Reddit’s r/SkinCareAddiction and on blogs. Users compare and contrast various formulas and study ingredient lists to try to identify cheaper dupes. Some products, like Good Genes, are so singular that it’s impossible to find a close match. However, proponents argued that Drunk Elephant’s C-Firma was a spot-on stand-in for CE Ferulic. The antioxidant and vitamin C ingredients, the stinky scent, the golden color, and the brand’s claims all convinced skin care enthusiasts they had found a credible dupe.

By law, beauty companies have to list all the ingredients in order of concentration from highest to lowest on their packaging. They aren’t required to list the exact amounts, but there are labs that can analyze and reverse engineer products, in a process called “deformulation.” As long as a brand doesn’t have a patent on a certain ingredient or formulation, copycats can get away with replicating these formulas. It’s similar to what happens in fashion all the time, since few brands can or do trademark their designs. But Skinceuticals does hold a patent for its formula.

Ironically, the reason many beauty brands don’t patent their formulations is that it makes them more susceptible to being knocked off. When a patent is filed, the specific details of the formulation become public information. This is apparently what happened to Skinceuticals, whose cocktail of vitamin C, ferulic acid, and vitamin E is mixed in a specific concentration and at a specific pH.

“One of the trade-offs of filing a patent is that the method for creating the product must be revealed. Many other brands have based their formulas on the information contained in the formula,” says a cosmetic chemist with experience formulating products containing vitamin C, who asked to be anonymous in order to comment on this case. “Some are apparent outright copies, whereas some brands will try to circumvent the patent by changing the solvent or other properties of the formula, like pH.”

Armed with a patent, L’Oréal obviously thinks it has a case against Drunk Elephant. A spokesperson for L’Oréal USA said in a statement to Vox: “We believe that the scientific inventions which make our products so innovative are a strategic and competitive advantage and we are committed to protecting our valuable intellectual property.” (As of publication time, Drunk Elephant did not respond to requests for comment.)

There’s big money in Big Beauty

While a huge company like L’Oréal can generally ignore smaller brands that rip off its products (unless it’s particularly blatant), it could no longer ignore Drunk Elephant. The upstart is likely now cutting into Skinceuticals’ sales of CE Ferulic. C-Firma was even crowned an Allure “Best of Beauty” winner this year, a designation that CE Ferulic has claimed three times. (Of course, a judge may find that Drunk Elephant did not infringe on L’Oreal’s patent.)

Drunk Elephant has been around since 2013, but it is just now hitting a truly global stage, and many industry watchers have been waiting for one of the big multinationals to acquire Drunk Elephant. In fact there have been rumors in the industry that Drunk Elephant might someday incite a bidding war between Estée Lauder and L’Oréal to acquire it.

Other small companies that produce similar vitamin C formulations will likely watch how this case plays out with a mixture of fear and interest. L’Oréal is asking for damages and an injunction for Drunk Elephant to stop producing the formula, which would be a huge financial blow to the company.

And for all those sleuths out there who determined that Drunk Elephant’s C-Firma was a great dupe for CE Ferulic? They’re probably feeling smug right now — and also possibly stocking up in case it disappears.

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