Ask HN: How do I "prove" my app doesn't infringe on existing IP?

You obviously cannot prove a negative to start with, but in the interests of being non-confrontational, you should just come out and ask what they are looking for in this proof.<p>I was once asked to prove that future litigation had already been dealt with (my reaction: WTF???) before somebody bought something from me. It turns out they were looking for a specific certification, which was easy enough to obtain.<p>The point being, they had asked the question in such an odd way, that it just confused rather than communicated.<p>Just ask them what they expect to receive from you in the way of proof, or that would be acceptable proof, and then go about getting it.

Document the provenance of every piece of code. Make a list of any third-party code you use, open source or proprietary, and a copy of the licenses.<p>At the top of each source file, make a comment with the name of the author, a copyright notice, and a pointer to your license file. If you've used version control since day 1, it can help you determine where your code comes from.<p>That should take care of copyright infringement.<p>Trademark and patent infringement might require hiring a lawyer to perform searches of relevant databases. This is going to be time-consuming and expensive for patents, and you may well end up infringing because of the awful situation of software patents. My best advice is to not mention patents and hope the customer doesn't bring up the issue.<p>I read somewhere that there's a ruling in the US that, unless you're a patent attorney, a court must presume that you don't know how to understand patents. And if you read a patent and incorrectly conclude that you don't infringe, that makes you aware that you infringe, and negligent because you didn't seek the advice of a patent attorney, and you're automatically liable for triple damages. But if you hadn't read the patent, you're only liable for single damages.<p>So it's better never to read any patents, ever, and pray you don't infringe, or if you do, that the patent holder isn't going to notice you until you're big enough to fight back.

Sadly, any developer of a 99 cent app might be sued for patent infringement, with no efficient and cost-effective way to find out ahead of time. Software companies have had this issue as long as software has been patentable (according to USPTO, anyway), but business insurance can be had for a price. The iPhone's conversion of software development into a "blockbuster" business (IE a few win big, most don't make anything), has encouraged small entities to enter the market who don't have the resources for insurance.

This is a liability issue. They don't want proof, they want you to <i>say</i> that you don't infringe, so if they get sued by patent trolls, their asses are covered.

IANAL, so take this with a grain of salt. Did they specifically use the term "IP?" Patents are IP, but IP is not necessarily patents. They could be talking about copyright, and possibly even trademarks. For copyright, if you wrote the code from scratch, you own the copyright, and you aren't infringing copyrighted IP. For 3rd party code that you reuse, you'd just need to demonstrate that you comply with the respective licenses.<p>Like chris_dcosta said, the best course of action is to ask for clarification. You might ask what exactly they'd like to see proven and how others typically go about proving the same (i.e. ask for examples).

This could become a new opportunity for auditing companies: Pay Arthur Anderson, eh of cause another one of the surviving big four auditors, a ridiculous amount of money just to "certify" your "non-infringyness".

it's awful hard to prove a negative... I would list all the companies with which I had IP agreements and state that X,Y,Z are the areas and this application wasn't built using their time and resources so there is no conflict and I'd offer to contact someone if they had a concern.

The only real answer to give you is to hire a lawyer whose specialty that is. The government (and perhaps any client) is going to take your answer and run it past their legal team, so unless you can bullshit to the extent that would pass actual legal scrutiny, it's probably best to not bother.<p>The hard fact of the matter is that you almost certainly <i>are</i> infringing on something in today's murky IP landscape, so the expectation is almost certainly less likely to get a document from you saying that you aren't infringing, rather, to get a document that explains the defensibility of your claims where you are infringing.<p>Interesting to me is that I've developed a broad set of applications for various government agencies, and I've never once been asked to prove anything similar to this. I don't know if you're responding to a bid with competitors, but my (wholly uneducated) guess is that perhaps one of the competitors brought it up in an effort to smear you, and even if your IP is defensible, the extra work involved might be enough to give them a win over you.