Organic is not a legal term. However, you should consider to look for an organic association which your country recognizes. For example in the US, the FDA governs what can and cannot be sold as organic food. Most country have strict labelling laws when it comes to foods. Here is a link: https://www.ams.usda.gov/grades-standards/organic-standards
Also, if you use a trademark without permission, that is also illegal, so food can hardly pretend to be organic. The risk is when you buy it off a random truck where there is no way to know.