Conclusion: It is not necessary to hire a lawyer if there is an IOU to bring a lawsuit in the court. Whether to hire a lawyer or not needs to be considered based on the case situation, personal ability and other factors. Legal analysis: There are obvious advantages in employing lawyers. With professional legal knowledge and rich litigation experience, lawyers can accurately analyze the case and provide professional services in drafting pleadings, collecting and sorting evidence, participating in court debate, etc., which helps to increase the probability of winning a lawsuit. However, if the facts of the case are clear, the dispute is small, the evidence such as the IOU is complete, and the parties are familiar with the litigation process and able to handle it by themselves, they can also file a lawsuit by themselves, which can save lawyers' fees, but they must complete the procedures of filing, providing evidence, and debating by themselves. Therefore, whether to hire a lawyer should be based on the complexity of the case, personal legal knowledge reserves and processing capacity and other factors. If you still have doubts about whether to hire a lawyer or encounter problems in the process of prosecution, you can consult with professional legal personnel to obtain more accurate legal advice and help.