I found a few posts but they were a bit ambigous a a lot was left to the uneducated imagination of mine. Title says it all really. Say I wanted to build a special type of laser, I do NOT want to sell OR profit off the device.

All I know is this device has a global patent, or perhaps a UK one, whats the difference if it was a UK patent and I was in the UK or what if it was a UK patent and I was in the USA?

Say if this laser was very good at cutting things in a 3D printer but I didn't sell any of the items that the 3D printer produced. Is this illegal?

I'm in the UK BTW. But I would also really appreshiate it if you just assumed it was what ever your country is.


  • 2
    Does this answer your question? Can I build something for personal use if it is patented?
    – user4657
    Commented Jun 13, 2020 at 4:23
  • The law is not different for Engineers. Often, the law does make exceptions for law enforcement and other government officials, however, I have not seen said exceptions in patent law
    – gatorback
    Commented Mar 18, 2023 at 12:44
  • It perhaps goes without saying, but the vast majority of patents ever obtained (including almost all patents obtained in the 20th century) have expired causing the patented idea to become part of the public domain. It is, of course, legal to design, build, and use an invention based upon an expired patent.
    – ohwilleke
    Commented Mar 18, 2023 at 21:24

1 Answer 1


Yes you can do this in the UK.

Section 60 of the Patents Act 1977 has a specific carve-out for this kind of activity:

(5) An act which, apart from this subsection, would constitute an infringement of a patent for an invention shall not do so if;

(a) it is done privately and for purposes which are not commercial;

(b) it is done for experimental purposes relating to the subject-matter of the invention;

So if you build and operate your laser without selling anything you are in the clear. You can also experiment with potential improvements.

There is no such thing as a "global patent": patents are issued in each country and the national law of each country applies (except for Europe). If an inventor wants patent protection in lots of countries they have to file for a patent in each country. So if this laser is patented only in the USA and you are in the UK then you could make and sell as many lasers as you wanted, as long as you didn't export them to the USA. And vice-versa for a UK patent and a USA engineer.

  • 1
    While this may be true in the UK, I don't believe it is true in the US (which the OP specifically asked about). Of course it is academic if there is no patent in the country the person is in.
    – Eric S
    Commented Jun 13, 2020 at 13:51
  • @EricShain True. Answer updated. Commented Jun 13, 2020 at 14:50

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