It’s old memories from the engineering school in Europe but I remember that a patent office is about collecting fees and documents, and won’t do any actual checks on the patents validities.
Some countries don't examine patents for validity, some don't search prior art but leave it to the applicant. But plenty of countries do check for validity - including USA.
Some countries don't examine patents for validity, some don't search prior art but leave it to the applicant. But plenty of countries do check for validity - including USA.