My business is trying to sell Lawn Aerator shoes, and I would like to know if this item holds any patent. I have searched on google patent, and found some patent information. However, I would like to know if the patent has expired:


There seems to be more patents relating to Lawn Aerator shoes other than the above link. Does anyone know if the lawn aerator shoes hold patents? Please let me know.

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Thank you, Y. Shin

2 Answers 2


You are looking for a "freedom to operate" opinion. Few lawyers will issue those anymore because of the malpractice risk.

You'll want to (a) identify the countries where you will sell the product; (b) disclose the product features (and preferably provide a specimen) to a lawyer in each country; and (c) have that lawyer confirm that there are no issued patents still in force that cover the product.

Your link was google.kr, so I'm assuming you accessed from Korea. If you plan to sell the shoes only in Korea, US patents don't matter (unless they get exported to the US). But Korean patents will matter.

I hate to give the very expensive "see a lawyer" advice, but see a lawyer. As one of the comments mentioned, variants of this have been around for a while, so if you are positive that you are implementing something more than 30 years old, you should be fine. Between 20 and 30 years, there are sometimes patents that exceed the 20 year lifespan (at least in the USA, due to patent term adjustments).


According to the US Public Pair, the patent has been listed as expired on June 2nd, 2005. It is listed as "Patent Expired Due to NonPayment of Maintenance Fees Under 37 CFR 1.362". Normally the term for a patent is 20 years from the filing date which should have extended out to November 22, 2019 in this case but the patent is clearly listed as expired. There might be a way to resurrect the patent by paying old fees and penalties, but at this point I rather doubt it.

With respect to prior art and other patents, you can click on the citations link in the page you listed to see what patents were either cited or cite the listed patent. This is a good way to find other relevant patents, but doesn't guarantee finding all prior art.

  • The cited patent refers to a particular improvement involving the use of hollow, steel tubes for aeration, especially embodiments incorporating a spring to eject the resulting tubular sod cores. Cited prior art for "lawn aerating shoes", as a concept, go back to the 1950s, or perhaps whenever the first mountain climber wore his or her ice crampons while mowing the lawn.
    – Upnorth
    Aug 13, 2017 at 21:44
  • @Upnorth Good observation. I encourage you to add your own answer.
    – Eric S
    Aug 13, 2017 at 22:09

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