Essentially, a patent is deemed valid in the US once the USPTO grants the patent, but it is up to the individual to then enforce the patent. This has to be done so without the assistance of the USPTO. According to the USPTO website, patents may be granted under one of the following classifications:
1) Utility patents may be granted to anyone who invents or discovers any new and useful process, machine, article of manufacture, or composition of matter, or any new and useful improvement thereof;
2) Design patents may be granted to anyone who invents a new, original, and ornamental design for an article of manufacture; and
3) Plant patents may be granted to anyone who invents or discovers and asexually reproduces any distinct and new variety of plant.
Invalidation can occur if another party challenges and proves the invalidity of the patent—usually through showcasing that the patent was already established previously.
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