I don't know about your state but in Ohio, it is illegal to tell any future jobs about anything other than your start date, your end date(if you have one) and if you actually worked there. So, a phone call would go something like this:
New job(nj): Hello. This is nj, I'm calling about a job reference for Dawg
Current job(cj): Yes. How can I help?
NJ: When did Dawg start and when was her last day?
CJ: She started here on June 20 and is still here. Has never been late and is a hard worker
So, a current job reference cannot tell a new job about any discipline issues or not to hire you. Illegal