Maintaining regular documentation, such as a log-book, can be an organization's most important asset when dealing with radiation protection issues, both normal and abnormal. When an organization is faced with litigation, proper documentation of events can ensure that a record is acceptable and, by extension, that the data itself is acceptable. A record of events will not preclude litigation, nor will it guarantee that an organization will prevail in a court of law, but it will provide evidence and credibility that could favorably affect the outcome of litigation. An organization can ensure that the documents it creates and maintains are as effective as possible by being aware of the legal consequences of documenting events and taking appropriate steps to conform to standards for admission of documentation. Misconceptions about log keeping such as recording only events that are likely to result in litigation, rather than recording all events, can prevent a record from being admissible as evidence. Because of the amount of effort and time put into documentation, and the reliance placed on its contents, it is important for an organization to ensure that a record will do what it is intended to do, namely to accurately record activities. Issues discussed in this article include the legal basis of documentary evidence, what and what not to record, when and how to record it, and how to strengthen the records kept.