Take the 2-minute tour ×
Ask Patents is a question and answer site for people interested in improving and participating in the patent system. It's 100% free, no registration required.

US6148942 "Infant stroller safely propelled by DC electronic motor"

According to Google Patents the 6148942 patent is status Lapsed and according to Public PAIR its status is Expired as of 2008.

Google Patents -

enter image description here

Public PAIR - enter image description here

Does that mean that a self propelled stroller as described in the claims if actually created/sold by third party would not infringe on the subject patent? What would be required for the the assignee to revive this patent, or is it too late for the assignee to recover his rights?

share|improve this question
It may be tangential but it appears the inventor and current assignee died in 2011. See this local newspaper article from Ohio –  Micah Siegel Aug 7 '13 at 17:36
add comment

2 Answers 2

A patent that has expired due to non-payment of maintenance fees can theoretically be revived by its owner by petition to the USPTO. The grounds are "unavoidable" and "unintentional". The criteria for establishing that it was unavoidable are a high bar:

(from 37 C.F.R. 1.378 ) 3) a showing that the delay was unavoidable since reasonable care was taken to ensure that the maintenance fee would be paid timely and that the petition was filed promptly after the patentee was notified of, or otherwise became aware of, the expiration of the patent. The showing must enumerate the steps taken to ensure timely payment of the maintenance fee, the date and the manner in which patentee became aware of the expiration of the patent, and the steps taken to file the petition promptly.

Unintentional is much easier to satisfy, at least initially to the USPTO. However the same CFR 1.378 says:

Any petition to accept an unintentionally delayed payment of a maintenance fee filed under paragraph (a) of this section must be filed within twenty-four months after the six-month grace period . . .

If the inventor is no longer living, the patent rights were most likely part of his estate.

The net of this is it seems very unlikely this could be revived. Even if it was revived, anyone who started production while it was expired may have "intervening rights" that would allow them to continue what they were doing. Of course this patent being dead doesn't mean there are not other patents that might cover the specific embodiments it describes or other aspects of something you might make.

share|improve this answer
add comment

Lapsed patents are patents that expired because the maintenance fee was not paid in due time.

Maintenance fees on US patents are due 3.5, 7.5 and 11.5 years after grant of the patent (in many other countries, they are due every year and are called annuities). US patents maintenance fees cannot be paid more than 6 months before the due date. They can be paid for an additional six months after the due date with a surcharge (this actually is a provision of the Paris Convention).

The USPTO provides a web application to view the payment windows for each maintenance fee. In this specific case: Maintenance Fees

The same application (and Public Pair) shows that the second maintenance fee (8th year) was not paid. Hence the lapse.

However, lapsed patents can be revived under certain conditions. Usually, including in the U.S., patents can only be revived if the proprietor convincingly argues that payment delay was unintentional or unavoidable. In the first case (unintentional), there is a specific time window of 24 months after the close date (in this case 11/21/2010) for filing such a petition, and Public Pair shows that none was filed for this patent. There is no time limit for the unavoidable reason, but it's much harder to argue.

Please note that patents are often grouped in families, with continuations or extensions in other countries. An applicant may let a patent lapse and abandon a patent to save on maintenance fees, while protection could be granted through other patents of the same family.

share|improve this answer
I thought the 24 month limit applied to both reasons but when I looked it up it seems to only apply to unintentional. cfr 1.378 –  George White Aug 7 '13 at 19:04
@GeorgeWhite Indeed. Edited accordingly. –  Paul Guyot Aug 7 '13 at 23:07
add comment

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.