Comment by qingcharles

Here's the thing. I've read thousands of police reports. Most police reports are super short and super vague. Most police reports are never read even once, even though a large percentage result in convictions. Most criminal charges result in plea deals. Most defendants will never see any evidence against them before pleading guilty†.

If, in the exceptionally rare case that a defendant goes to trial, an officer has to testify, it is probably on average a year after he wrote the report. He will be sat down just before trial by the prosecutor and shown his report and asked to read it. On the stand he generally will not have his report available to reference and is supposed to use his memory, but this will be corrupted by his reading of whatever is in the report he read a couple of hours before. If his report is full of inaccuracies he will almost certainly testify under oath to those.

†This situation has changed very slightly in the last few years with lawyers now supposed to verify the probable guilt of their client before recommending a guilty plea.