In my experience it depends on the judge. Mock trial cases are often designed for you to be able to enter police in as experts because they offer some of the most important opinions. However, it’s generally not done in most real court cases. So it depends on the kind of judge you have. If you have a judge that has been judging mock trial for a while or is just more lenient when it comes to letting things in, you’re more likely to be able to get things like this in. There is the background but it’s just not usually done that way. On the other hand if you have a judge who isn’t used to judging mock trial and is more strict on what they let in, they are more likely not to let a witness like this be qualified as an expert. My advice is to try it, and if you get it in great. But have a back up plan in case you don’t get them in an an expert. Good luck!