So you have an invention and worried that people may be able to copy it by adding their own twist to the design to copy your patent. This is why employing a patent attorney to write up your patents is very important. If you lodged your own patent application you might miss a few obvious things that other people may find ways around.
We have a shelf that is hung up using nails. What is to stop someone with coming up with the same idea but instead of using nails, they use screws?
The best way to defeat things like this happens is to broaden the patent so it covers all avenues. Instead of just specifying nails in the patent, specify fasteners and then in the specification state fasteners may be screws, nails and any other types of fasteners.
Since the mid-eighteenth century courts have recognised “Doctrine of Equivalents”. This was brought about to protect patents further as for inventors to not lose the will to innovate.
If the product / patent performs substantially the same function in substantially the same way to obtain the same result, then it infringes the patent under the Doctrine of Equivalents.
So in the case of our shelf. Fitting the shelf to the wall with screws instead of nails will infringe on your patent even though you don’t specify screw in your patent.
The Doctrine of Equivalents helps assure you get the strongest patent possible and ensuring a competitor cannot pirate a patented invention by making some insignificant changes.
In most cases the competitor won’t be able to get around your patent as the courts would invoke the Doctrine of Equivalents.
Generally speaking, if done correctly the answer is no.