our T&Cs are water-tight, and the docs he has been sending large extracts from have "Confidential - For internal use by XYZ client only, not to be sent to third parties without our written consent" plastered all over the cover page and little copyright notices on every page throughout. charliefleabag is right, I think the problem we have here is a little twerp who doesn't understand basic principles of business etiquette.If I said to him that, by sending a 20-page report to one of our competitors, he has essentially transferred say 200 person-days of intellectual capital to one of our competitors (and I'm talking about document style/presentation, implied methodologies, and so on), I have no doubt that he just wouldn't "get it" and would think it carries the same value as his own crappy powerpoints which typically consist of 20 pages of size 36 font bullet points.I think what I'll do is let this one go, but in our next proposal to them I'll add a line to the fees section that says something like "Our reports are intended for use by XYZ's own employees only. We have priced this project based on written deliverables being used by XYZ's own employees only. If you would like to share the reports, or extracts of the reports, with third parties (including but not limited to companies that we would consider to be our competitors), a standard licence fee applies (see section 10.4 of the Terms and Conditions attached to this proposal for details), however we may be willing to waive that fee in certain circumstances; all requests should be made to us in writing." I'll also add a new line to the reports themselves saying "Not to be shared with third parties - licence fees may apply; see proposal dated XYZ for further information".Then in the T&Cs I'll add a line that says something like the licence fee is 100% of the project value and that this fee takes into account that the reports will typically contain 200 person-days of intellectual capital beyond that which has been created specifically for the client.I know it might be considered an "unfair" term, and it would seriously cheese some people off, and I need to word it better than that above, but there may be some mileage in it and at the very least our little twerp friend might have some explaining to do when his boss receives an invoice which is double what he expected and it transpires it's because he's been leaking like a colander... (even if we later issue a credit note)...This guy knows what he is doing is wrong, but doesn't give a $hit. That's what bugs me the most.