A legal argument or assertion of fact that is not baseless or without substance; that has at least a slim chance of success or being proven – it is not certain to fail. Usually used to refer to a legal argument that is not so weak that it is an abuse of process to introduce it, i.e., “at least colourable.” An argument that, even if it is weak, can be made in good faith, or a factual assertion where there is at least some supporting evidence or some reason to believe that supporting evidence exists and can be found. An extremely weak legal argument or factual assertion is sometimes referred to as “barely meeting the smile/laugh test.” See Rule 11. By contrast lawyers are generally ethically precluded from advancing arguments or making factual allegations that are not “at least colourable” and can be sanctioned if they do so.
In intellectual property due diligence in for example a merger or acquisition, the records of title of a business’ IP assets should be carefully considered to determine if any third-party might have colourable claim to own the intellectual property or have an unexpected pre-existing license. Typically this focusses on finding clear assignments or licenses (and any termination clauses), and studying employment, consulting and contractor relationships, to determine how the business owns the intellectual property or has rights to use it, often focussing on employment and consulting agreements and shop right(s). An inability to properly demonstrate clear ownership, or a defeat colourable claims or potential claims from a third party can be seen as a cloud on title, which can be expensive to remove. For this reason it is always wise to address ownership issues early.
Note: American English spelling is colorable; British English is colourable.