Copyright infringement is always an issue when making replica firearms since most airsoft manufacturers base their designs on real steel products, thus not only trademarks are licenced, but even the design of the product must get approval from the original manufacturer, if that is the case. We always get news of court cases, or threats of court cases every year. The big one was the Magpul Masada which was built by A&K.

And this is not only with airsoft manufacturers, even the real steel manufacturers encounter issues when releasing a product that looks similar to a competitor's product.

Such is the case with the American Tactical Imports (ATI) GSG-522 which on first impression is an MP5 of H&K which was the court case on the first place. So in order to have peace of mind, ATI made some changes. According to the Firearms Blog:

It turns out H&K had initially sued them over a long list of complaints. Most of these, the trade dress infringement being the sole exception, were thrown out of court. By simply making some design changes to avoid the GSG-5 being confused with the H&K MP5, ATI has been able to bring the gun back into the market under the GSG-522 name. The GSG-522 design was signed off by H&K and no royalties are required to be paid.

At Weapons Cache, a few more details:

Where H&K got to take their ball and go home, part of the agreement was that with a few changes to the look of the gun, GSG could continue to manufacture and ATI could continue to import a mechanically identical gun with subtle exterior changes to differentiate the gun from the original licensed MP-5 design, now to be made by Umarex.

Well, we know of one airsoft manufactuter which is about to release something that follows the same pattern. We were expecting them to release the product last December, but it may seem that they changed their minds and maybe do some more "subtle exterior changes" to make it look like they are not infringing on someone else's original design and avoid litigation and licensing issues.