Q: Can police legally revise a report affecting my case?

A: Yes, the police are allowed to correct thier mistakes in police reports. Typically, how they do this is that they create a "supplement" which is just an extra page and the end of the report where they write all the corrections to the original report. Believe it or not, the police don't even have to correct their police reports but can still show up at trial and then testify that there were mistakes in the report and then verbally correct them while on the stand. This seems unfair but it is allowed and is not illegal. If either of these forms of correction happen, the only benefit you get as a defendant is that your lawyer can attempt to reduce the officer's credibility by saying that if they messed something up and needed to correct thier mistakes, then how do we know that the officer didn't make other mistakes. Sometimes if you reduce the officer's credibility enough, the judge or jury will not believe them at all. Likewise, if there are supplements and many corrections in the police report, sometimes your lawyer can negotiate with the prosecutor that the officer will be uncredible and it could get you a better plea deal or the case dismissed depending on how big the mistakes were that needed to be corrected. This is very specific to each officer on a case-by-case basis.

One thing I will add, is that it sounds like in your situation that the officer modified the original police report and did NOT do a "supplement". If that is true, that would be extremely rare but still not illegal (as far as I have ever seen). All the same arguements I listed above still apply and should be even more effective in negotiations with a prosecutor because most prosecutors do not want to have to explain to the judge or jury that the officer deleted and re-wrote parts of the report as opposed to creating a supplement.

Hope this helps. You should also do a free consultation and hire a lawyer to represent you because they might be able to find more mistakes than you did.