## Facts

- Bayer Company, Inc. sold acetylsalicylic acid in the United States under the name “Aspirin” and claimed ownership of both a registered and common-law trademark by assignment.
- A U.S. patent covering acetylsalicylic acid issued in 1900 and expired in February 1917; Bayer filed suit in May 1917 shortly after expiration.
- During most of the patent period, Bayer marketed “Aspirin” primarily to manufacturing chemists, physicians, and retail druggists, asserting that “Aspirin” meant Bayer’s manufacture.
- For years, consumer-facing bottles often used “Aspirin” prominently without clearly identifying Bayer as the source; Bayer began conspicuously using “Bayer – Tablets of Aspirin” only in October 1915.
- Significant quantities of acetylsalicylic acid reached the U.S. market through patent infringement, contributing to widespread public exposure to the term “Aspirin.”
- After patent expiration, United Drug Company and others sold acetylsalicylic acid using the word “Aspirin,” contending the term was the product name rather than a brand.
- Bayer sued in equity seeking to stop use of “Aspirin” and to obtain relief for alleged unfair competition in United Drug’s marketing.

## Issues

1. Whether “Aspirin” had become generic for acetylsalicylic acid in the eyes of relevant purchasers, defeating Bayer’s claimed exclusive rights.
2. Whether trademark significance could persist for some buyer groups even if the term was generic to the general public, and what scope of injunctive relief would be proper.
3. Whether United Drug’s use of “Aspirin” and related marketing practices constituted unfair competition by creating avoidable source confusion.

## Decision

- The court held that, for the general consuming public, “Aspirin” had become the name of the drug and was not protectable as an exclusive mark in retail consumer sales.
- The court held that, within the drug trade (manufacturing chemists, physicians, and retail pharmacists), “Aspirin” still indicated Bayer as source and warranted protection in that sphere.
- The court entered a limited injunction restricting United Drug’s use of “Aspirin” in trade-channel sales where the term signified Bayer’s product.
- The court permitted United Drug to use “Aspirin” in consumer sales, conditioned on clear labeling to identify United Drug as the manufacturer and reduce confusion.
- The decree granted Bayer only part of the relief sought.

## Legal Principles

- Genericness turns on purchaser understanding: if buyers understand a term to mean only the kind of goods, the term cannot be monopolized as a trademark.
- The name of a patented article is not automatically free of trademark significance upon patent expiration; protection depends on whether the term functions as a source identifier (secondary meaning) for the relevant audience.
- Consumer perception may differ by market segment; a term may be generic for the public yet source-identifying within a professional trade.
- A trademark owner’s marketing practices can contribute to a term’s loss of source significance, especially where packaging and promotion present the mark as the ordinary product name.
- Where a term is generic to the public, relief may be limited to measures preventing confusion (such as prominent source labeling) rather than barring all competitive use of the term.

## Conclusion

The court treated “Aspirin” as generic to ordinary consumers but still source-indicating among professional purchasers, and it crafted a limited injunction that preserved public use of the generic name while requiring sales practices that reduced confusion in trade channels.


Bayer Co. v. United Drug Co., 272 F. 505 (S.D.N.Y. 1921)