For the most part, opinion should not be used in a police report. A police report should be a statement of facts. The police report will be used in court and can be impeached by a defense attorney if it gives a lot of opinions. A police report with opinions in it will tend to make it look like the police are biased against the defendant. Therefore, police reports should typically not have opinions and should stick to the facts.
There are times when it may be appropriate to give one’s opinion. This would only happen when this is an expert opinion based on your experience and training as a police officer. However, it would be important to back this opinion up with fact. For example, if you were going to say in your report why you decided to initiate pursuit of a suspect, you might say that, in your professional opinion, the suspect was acting in a way that indicated that he might be guilty of a crime. However, it is definitely best to articulate how he was acting.
Thus, it really is not appropriate to put one’s opinion in a police report unless that opinion is supported by facts.