If you're interested in trademarks and design, you may have heard that you only need to alter a logo by about 20 to 25 percent in order to claim it as your own. It can be inspired by a logo that already exists and is in use as long as it differs enough that it appears to be its own design. Is this true?
It is true that a logo needs to be different than existing logos to be legally used, but the 20 percent rule -- or 25 percent rule, depending on whom you ask -- is little more than a myth. There is no percentage that is applied to cases like this.
Essentially, you just need to make a logo that is different enough that people don't see it and instantly think it's stolen from the existing logo. It's said that it can't have a "substantial similarity" to the existing logo. As you can see, this does create a bit of a gray area, as that phrase is definitely open to interpretation.
The reason percentages are not used, though, is that there is no real way to calculate them. If you were to steal a work of text and change 20 percent of it, it would be something quantifiable. How much of the text is the same, and how much is different? With a visual representation or a work of art, though, it's tough to pin that down and everyone may see it differently. Since a numerical value can't be used, it has to be left a bit open-ended.
Those who own trademarks in California must know their rights, especially when the another party is trying to claim that infringement is legal based on the 20 percent rule.
Source: Graphic Artists Guild, "Trademark, Copyright, and Related Legalities," Linda Joy Kattwinkel, accessed July 11, 2016