Absolutely. I won’t go into all the conscious and unconscious biases cops have. (But if you Google “witness lineup issues” or read Balko’s blog in the Washington Post you can see a lot of it.) But what about when there is an after-the fact investigation and a police report prepared?
First off, since the cop did not witness the incident, s/he will have to rely upon witness’s statements and/or other physical evidence at the scene. Sometimes the officer will make a drawing or take photographs, but not every case gets the full CSI/NCIS treatment. And sometimes there is no “Abby” to figure out that they got it wrong.
So how do you know if the cop got it wrong? Look at the elements of your case, consider all other factors, and how the facts would support your claims. What other witnesses are there? Are there alternative explanations? What incentives/motivations of the various witnesses are there that could explain the witness statements. Check into external factors (cell phone usage, alcohol/drugs, other distractions, etc.).
Don’t forget to examine the improbable. I had a case once in DC where there was an accident in which both drivers SWORE they had a green light. I *knew* they both couldn’t be correct. But …. It turns out that one of the lights had been hit by a car a few days earlier and rotated 90 degrees. So it *looked* like both had a green light. Everyone, including the police, *knew* that they couldn’t both be right but they were.
Good case for me too against the city.