That’s right. Even a granted valid patent cannot prevent a competitor from copying your invention. All a patent can do is change the competitor’s assessment of risk. This can be very valuable, of course.
So, having good patent protection will have a strategic effect on your competitors, but will probably not work as an absolute barrier. This is true even if you patent appears valid and appears to be infringed and is recognized as such by your competitor!
First example. Competitor ACME invested $100M in developing and marketing a product. Will ACME throw that money away just because you have a patent? ACME may very well prefer to risk a lawsuit.
Second example. You are a small startup, with a patent infringed by a ACME. ACME may well decide that in any legal contest you will run out of money first, and risk an infringement.
Third example. You have an innovative product. ACME likes the market. Should ACME buy you or copy your product? If your patent protection is good, ACME may well decide to buy you out. If your protection is even better, ACME may decide not to buy your competitor.
This means that the value of your patent portfolio depends also on the expected behavior of your potential competitors/partners. A later post will relate to the type of copying.
So, how will your competitors evaluate your patent portfolio?
p.s. A good idea or product will usually be copied more vigorously if it has no patent protection, and there is a trade-off between value of protection and damage due to publication, which needs to be considered.