A common yet misguided belief is that patents can be avoided by simply changing a protected invention by 10%. This myth has absolutely no legal basis whatsoever and its source remains unknown.
This “10% myth” may be borne from the fact that patent applications prepared without the assistance of a patent attorney usually provide no meaningful protection. Indeed, avoiding infringement of a self-prepared patent application can require no changes to the invention at all.
In reality, it is unclear how it would be possible to change any invention by 10%. If an invention was to relate to a chair, for example, would it be changed by 10% if the legs were lengthened 10% or if one leg was removed altogether? These types of trivial design variations would typically not avoid infringement of a properly prepared patent, if there was indeed infringement in the first place.
The scope of protection afforded by a patent can only be determined through careful consideration of the claims within that patent. The claims can be divided into one or more independent claims from which all other claims depend. As a rough rule of thumb, the ability to design around a patent becomes easier as the length of the independent claims increases, and the scope of protection afforded by the patent thereby decreases.
In general, patents relating to new technologies or technical fields which are not extensively developed, have the potential to afford the broadest scope of protection. These patents would tend to have broader claims with fewer features needing to be added to distinguish the inventions from existing inventions in the field. In terms of obtaining strong patents in a particular field, it is generally a matter of “first in, best dressed”.