Project notebooks serve as official documents for patenting. While working on a project or design that will have controversial or economic ramifications, you should always have a supervisor or advisor sign and date your notebook. This way, you can vouch for your project's evolution. For legal purposes, it's especially important to know that the history you've documented is in fact true and has the correct time schedule. Legal disputes require you to prove that your work was completed within a certain time frame. When it comes to invention, timing always plays a major role.