Taking inspiration from another design

The stop sign shape is a good example.

The stop sign is designed to get your attention. Bold lettering and red and white reflective paint is easy to see under heavy weather conditions. They have 8 edges because it reflects urgency better than a sign with fewer edges, like a rectangle. People are trained and conditioned to react instinctively to a stop sign. We all see them regularly. This also means we react to things that remind us of a stop sign, such as the octagon.

The shape of ADT or CPI security lawn signs share this shape. They get our attention in a similar fashion. The signs also use white text and some use a similar red. ADT reflects security through the color blue, but CPI looks like it’s stealing from the stop sign design. But it’s within their legal right to use their design.

It’s obvious when you see a stolen design. There’s a threshold. If you steal subtly enough from another design, it’s inspiration.