A good slogan can carry a whole brand. But can you protect one under copyright law in Japan? And if your new tagline looks a lot like a competitor's, are you infringing anything? With more teams now drafting copy with generative AI, these questions come up more often.
This guide explains how Japanese courts treat catchphrases, why trademarks matter more than copyright in practice, and how to use AI for copywriting without walking into legal trouble. It is written for marketers selling into Japan and for Japanese brands taking their messaging overseas.
The short answer: short slogans are rarely protected by copyright
Japan's Copyright Act defines a work as a creative expression of thoughts or sentiments (Article 2(1)(i)). A catchphrase is an expression, but because it is short and often uses common wording, Japanese courts usually find that it is not a copyrighted work.
There are exceptions. When the rhythm or combination of words clearly reflects the author's individuality, a slogan can be protected. Even then, protection only covers expressions that are very close to the original.
- Advertising slogans of around 20 characters leave little room for creativity and are usually not protected
- Slogans with a distinctive structure, such as the 5-7-5 rhythm of Japanese verse, have been recognized as works
- Even a protected slogan is not infringed by something merely similar
- In practice, the bigger risk is trademark law, not copyright
Why short phrases get little protection
Copyright protects expression, not ideas. When you describe a product's benefit in a few words, the range of possible wording is narrow. If the law let one company own every short phrase, others could no longer write ordinary advertising.
So Japanese courts look closely at how much room the author had to choose a different expression, and where the author's individuality actually shows.
Two court cases that draw the line
Not protected: an English course's catchphrases (the Speed Learning case)
A company selling an English listening course sued a competitor whose ads used wording very close to its own, such as a phrase meaning "Just listen to English like music, and you'll grow to love it."
The Tokyo District Court (March 20, 2015) and the Intellectual Property High Court (November 10, 2015) both held that the phrases were not copyrighted works. Advertising copy has to describe a product briefly, often within a character limit, which leaves little room for individual expression.
The takeaway for copywriters: nearly identical wording did not amount to copyright infringement.
Protected, but narrowly: a traffic safety slogan
In another case, the author of a child-seat safety slogan, which translates roughly as "I feel safe: a child seat beats Mom's lap," sued over a later slogan meaning "A child seat beats Mom's arms."
The Tokyo District Court (May 30, 2001) found the original slogan to be a work, citing its 5-7-5 rhythm and word choices. But it found the second slogan not similar enough, and the Tokyo High Court (October 30, 2001) also rejected the infringement claim.
Even when a slogan qualifies as a work, only the expression as a whole is protected. That is the realistic scope of copyright for catchphrases in Japan.
Watch trademarks more closely than copyright
Most real disputes over catchphrases involve trademarks. Once a phrase is registered with the Japan Patent Office (JPO), its owner can stop others from using it for the designated goods or services.
The JPO refuses a catchphrase that consumers would see only as advertising, because it lacks distinctiveness (Article 3(1)(vi) of the Trademark Act). For example, 「たっぷりカリフォルニア太陽の味」 ("plenty of California sunshine flavor") for meat products was refused on this basis.
However, a phrase that can also be recognized as something more than advertising, such as a coined expression, can be registered. If a competitor has registered its slogan, using the same words in the same field can infringe the trademark even when copyright is not an issue.
- Check registrations in J-PlatPat, the JPO's free database, which has an English interface
- Consider registering slogans that will carry your brand
- Parodying a famous slogan can also raise unfair competition issues if it strongly evokes the original brand
Borrowing from famous slogans: what is fine and what is not
Studying great copy is fine. What matters is what you borrow.
- Fine to borrow: structures such as questions, contrasts and numbers; how to build rhythm; how a line moves the reader
- Avoid: copying distinctive wording, changing only the ending, or parodies that call a specific brand to mind
A contrast pattern like "Small, yet powerful." is an ordinary structure used everywhere. Echoing a line that has become synonymous with one brand, on the other hand, can look like copying even when it is legal, and that can cost you trust.
What to do if someone says your slogan infringes their rights
- Check the facts: is the claim based on copyright or trademark, and what registration or evidence supports it?
- Do not ignore it: reply by any stated deadline, at least to confirm receipt and that you are reviewing it
- Consider pausing use: limit potential damages while you assess the claim
- Get professional advice: a lawyer for copyright, a patent attorney (benrishi) or lawyer for trademarks. Do not admit or deny anything on your own
- Resolve it: obtain a license or change the wording if needed
Using AI to write slogans: what to watch for
Generative AI can produce dozens of slogan ideas in minutes. Two legal points deserve attention.
AI-generated copy may not be your copyrighted work
In General Understanding on AI and Copyright in Japan, compiled on March 15, 2024 by a subcommittee of Japan's Council for Cultural Affairs, the government's advisory body states that output is not a copyrighted work when the human instructions remain at the level of ideas. Whether a human made a creative contribution is judged case by case.
Short slogans are already hard to protect, and copy left entirely to AI is even harder to claim. If a slogan matters, protect it with a trademark registration rather than relying on copyright.
AI may reproduce existing slogans
Because AI models learn from huge amounts of text, they sometimes return a famous slogan, or a light rewording of one, as if it were new. Using it as is can lead to trademark claims or accusations of copying.
A safer AI copywriting workflow
- Be specific in your prompt: target audience, product strengths, the feeling you want, and where the copy will appear
- Do not paste competitors' slogans into the prompt
- Have a person choose and refine the output, and keep a record of the human edits
- Before using a final line, run an exact-match web search and check J-PlatPat for identical or similar marks
- Consider a trademark filing before launching a slogan that will carry your brand
AI is best at producing volume and widening the range of angles. Leaving the final choice and polish to people makes it easier to stay both original and safe.
What matters for slogans going forward
- Write for one person: the more specific the reader, the stronger the line
- Stay true to the brand: choose words that only your brand could credibly say
- Check how it reads abroad: when expanding overseas, review the translated meaning and local trademarks
- Test with data: run A/B tests in ads and on social media, and keep what performs
- Treat AI as a thinking partner: AI for ideas and testing, people for judgment and finishing
Key takeaways
- Short slogans are rarely protected by copyright in Japan
- Distinctive slogans can be protected, but only narrowly
- Trademarks are the real risk. Check J-PlatPat before you launch
- AI-written copy is hard to claim as your own work and may overlap with existing slogans
- Protect key slogans with trademarks, and use AI for ideas and testing
This article provides general information as of November 2026 and is not legal advice. Consult a qualified lawyer or patent attorney in Japan about specific cases.
Sources
- Intellectual Property High Court, judgment of November 10, 2015 (Japanese)
- Tokyo District Court, judgment of March 20, 2015 (Japanese)
- Council for Cultural Affairs subcommittee, General Understanding on AI and Copyright in Japan (March 15, 2024, Japanese)
- J-PlatPat (Japan Platform for Patent Information)
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