Massachusetts,
Hey Guys,
I was wondering how long patents last for after the date of issuance. I was also wondering how I can make sure the patent is expired without spending too much money.
Thanks
It depends mainly on when the patent was filed for. If the patent was filed prior to June 8, 1995, then the patent expires either 17 years from the date of issue, or 20 years from the "earliest effective filing date," whichever results in a longer term. If the patent was filed after June 8, 1995, then the patent term is 20 years from the earliest effective filing date.
The patent term may also be lengthened or shortened due to delays in prosecution or terminal disclaimers. If either of these apply, they will be listed on the front page of the patent.
The earliest effective filing date is the filing date of the earliest patent from which the patent in question derives priority.
