Is this correct, even though we are not doing this for purpose of selling it? Isn't a patent in public domain? How would such a law be enforceable?

Patents are NOT in the public domain until they expire - typically now 20 years from the filing date - if all maintenance fees are paid. It is an act of infringement to make, use, sell, or offer for sale, a patented invention - unless you have permission (i.e., a license) from the owner. The fact that you may want to license a patent likely means that you are (or could be) in contact with the owner - so ask for a "test drive" if you want to be completely safe from any charge of infringement. You can ask that it be done "free of charge" - but that decision is the owner's to make.

First, a patent is not in the public domain unless it has expired. Second, you are correct. The right conferred by a patent grant is, in the language of the federal statute (35 U.S.C. ?101) and of the grant itself, ?the right to exclude others from making, using, offering for sale, or selling the invention in the United States or importing the invention into the United States.

There is a common-law exception to patent infringement for de minimus experimental use. It is a narrow exception and you should have an attorney help yo to make sure that your planned experimental use qualifies, but there is an exception that can allow you to test the invention without having to pay the patent owner.

A patent holder has the absolute right to determine who can use and/or product the item. If the patent holder wants to license the product, he/she/it should cooperate with the potential licensee, after the licensee provides certain protections such as a nondisclosure agreement. A patent is most definitely not in the public domain until the term of protection ends.

Technically, you would likely need to obtain a license from the patent owner to test the invention for your application. The owner of a patent has the exclusive right to make, use, sell, and import an invention protected by a patent. Testing the invention for your application would likely involve making or using the invention; thus, you would likely need a license from the patent owner. A patent does not become part of the public domain until it expires.

Yes, it is true that the patent law is written in such a way that prevents anyone from making and using a patented device. If it can be shown that the infringement is deliberate, the patent holder can recover triple damages (these are not likely to be much without commercial concern) and lawyer's fee. Not worth the trouble. Find a way to test with permission (in writing).