I see a large number of "When does Patent X expire?" questions being marked as duplicates of How do you determine a patent's expiration date?, with zero effort to edit, re-tag or answer the question. I don't think this is constructive, because most of these questions are being asked by new users who are likely not familiar with patents, patent law, or the associated terminology. It takes several years to really understand these things, and that cannot be expected from a casual user who simply wants a direct answer to a direct question.

I know the information is out there on how to calculate patent expiration dates. I am not arguing the importance of providing that information. But closing these questions as duplicates is non-constructive if not downright irresponsible.

Remember, these questions are being linked to directly from Google Patents. This is a huge deal. Aside from Wikipedia and a small handful other sites, Ask Patents is in a privileged position on the internet due to this blessing from Google and the USPTO. Every answer that is posted here may potentially impact case law and commercial entities. With that in mind, there should be at least some attempt to provide a constructive answer instead of simply creating more dead ends. Too many dead ends will kill Ask Patents. If this community is removed from Google, it might as well not even exist.

Here is what I propose:

A more constructive approach would be (at minimum) to provide the link to the other question in a comment, and to give the original poster or any other user a chance to answer the question directly. I've already gone through several of these, and every one seems to have some unique criteria that affect the expiration date. It is easy to overlook some features of a patent and arrive at an incorrect expiration date unless you have seen each specific condition before. The answers to these questions can be used as a teaching tool for new users as well as some established users in this community, and they provide both a permanent record for others who are looking for the same information, as well as a way to contest or update an existing answer. A closed question offers none of these possibilities.

Cases in point:

Herceptin (US 7,560,111 B2) patent expiration

This is an incredibly important patent, and the question deserves an answer. Unfortunately, I can't provide an answer because it has been closed as a duplicate of a question regarding the expiration date of Patent US 7,055,282 B2. These patents are not related, and therefore the question should not be considered a duplicate. Cite the answer to that question in a comment, certainly. But don't mark it as a duplicate. It is not a duplicate. We are talking about the expiration of a completely different and industrially important patent. Not to mention, the first thing a user will see when they click on the Google Patent discussion link for the Herceptin patent is not a constructive answer to a question, but a "marked as duplicate of the expiration date for "Hydroponic plant cultivating apparatus". This is completely misleading to a casual user who is using Google to find information on a specific patent.

When will patent US 6,797,357 expire?

Marked as a duplicate but was thankfully wasn't closed yet. The answer to this question has significant commercial ramifications, as it affects 40 different international patent applications and issued grants. Not only that, but it is an illustrative case of a divisional application filed after 1995 with a priority date that limits the enforcement.

What is the expiration date of patent US 6,676,109?

There was an incorrect answer here (it is very easy to miss important details if you aren't familiar with them), but at least another answer could be posted. It turned out to be an illustrative example of a continuation application with a high chance of a missed maintenance fee payment that will be worthy of an update in the very near future.

These are all incredibly important things, relevant to huge (in real dollars) patent families. Why should these be closed as duplicates?

  • 1
    good and detailed question i would like to have update on same.
    – Pushpak
    Jul 20, 2015 at 5:11

2 Answers 2


Pushpak raised what I think is a really key point in this: our job is to show users how to find the information they need. We need to be complete, but we also don't want to see the entire site turn into just a database of individual patent expiry dates. The Stack Exchange system is much stronger when data is presented with reproducible steps, and when we funnel useful information about an individual topic into an easy-to-find, voted-on list of answers.

I see your point, though. We definitely don't want to be scaring new users off. It is a Q&A site, so if we're failing to answer users' questions, well that's just not very good at all. Not to mention, especially as we work to help Ask Patents to grow, we can't always force it into the same patterns as we might be used to on other Stack Exchange sites, because it's just been brought up very differently.

Ultimately, I'm not convinced that closing as a duplicate is the bad-guy here. While I definitely think your concern is justified, I stand by the point that "what's the expiry date for [this patent]?" is a duplicate, and should be answered, by "How do I find the expiry of a patent?" We want users to go back to that canonical resource, both to reduce redundancy and to improve the chances of a person in the future being able to answer their own question with the help of information we present to them (a big win in the Q&A model).

To the point of scaring off new users, I think that's also valid. And as I mentioned, we definitely, even more than some more established sites, don't want to be doing that. But at the same time, I'm still not sure the "duplicate" status is the issue. I've been playing with Stack Exchange for a little while now, so it's hard for me to look at it with fresh eyes, but I like to think that a user who asks a question, and is consequently pointed at a different question that answers what they wanted to know, should be happy. That's better than having to wait around for a tailored response, at least in some cases.

If you stick with me for a little bit and figure that the primary issue here isn't closing as a duplicate, that leaves the culprit to be, if anything, the existing canonical resources available through that question.

I don't know whether you will agree with me up through here, but if you do, the question that results is:

How do we find a good canonical answer to the question of how to find an expiry date that:

  • doesn't scare off new users with its complexity,
  • completely answers the question, and
  • doesn't mislead anyone to think a patent is or is not valid, since as you mentioned, this can be a pretty important issue.

And to that, I'd start with asking yourself how you would answer any of these individual questions. Fortunately for us, while the rules on when a patent will expire can be a tad confusing at times, there are rules, so can we follow those rules down a path that teaches new users who ask that question how you'd find the answer, such that they can find it themselves?

Of course, also as Pushpak pointed out, if the canonical resource doesn't completely answer the question, the user is free to edit and/or comment to make their case. If that option isn't abundantly clear to users, I think that's an issue with the UI, as compared to the actual closing process, and it should be brought up on Meta Stack Exchange.

But honestly, worse than that, I think the big problem is just that we get a lot of users looking through patents on Google, having a question, posting it here thanks to the "Discuss" button, then forgetting by the time any of us see it that they even asked something. That's mostly just a guess, and I don't have the data to support or reject it, but it's the impression I get from a lot of the questions that we do give really good and tailored answers for, and never hear from the user again.

  • Thank you for your time and detailed explanation, you are absolutely right we have some limitations i will work over your idea and make a complete comprehensive answer on expiry calculation.
    – Pushpak
    Jul 28, 2015 at 13:49
  • I don't see a compelling reason not to allow detailed step-by-step instructions as answers customized to a particular patent, even if it results in some overlap or duplication of responses. The outliers, those patents that fall outside of the “de-facto” response that is being linked to, are the ones that provide the most instructive examples. Anyone who wants to learn how to handle special cases for patent expiration can find them through the expiration tag. I maintain that closing them as duplicates is bad. Add a comment to the generic response and allow them to eventually be answered.
    – Parker
    Aug 15, 2015 at 14:00

Thank you for your question it really raise some questions on marking of duplicate due to expiration date. but in my way of moderation i feel every marking or flag itself says that if your question is not answered by earlier answer user is open to ask new question with original question as link.

Based on my interaction with other moderators and users, we restrict to such flags to filter out popup question with only expiration in demand. if asker is more involved and detailed their are instances we give them detailed explanation how to deal with situations.

I got more insight from our Moderator 'Mathew' he said to me once we just don't want to give answer we want to provide methods which will solves future similar questions. and by any mean if asker has any doubt we are here to solve it. This motto derives my way of moderation but I would really like if Robert and Mathew give more detailed insight on same.

  • I am 100% in support of providing the method. I am also 100% in support of leaving these question open so that they may be answered. Closing a question removes any possibility of the question being answered, and acts as a deterrent against discussion of the question. I think new users should be given a chance in this case. We already know that they have an interest in a specific patent, so the expiration questions may well lead to follow-up questions and a more active community.
    – Parker
    Jul 20, 2015 at 12:55

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