This study aimed to investigate the opinions held by police officers regarding discussion between witnesses. Experimental evidence suggests that such discussion can contaminate evidence. Previously, it had been assumed that co-witnesses commonly discuss the event with one another and that legal authorities, such as police officers, would discourage co-witness discussion, but this had never been assessed. To examine this issue, a survey of 145 police officers was conducted. Police officers reported that they believe the majority of witnesses discuss the event with one another. Even though police officers were inclined to believe that co-witness discussion is detrimental to memory, this opinion was not universal and many police officers suggested that there are possible advantages of co-witness discussion. The majority of police officers reported that they had received training regarding co-witnesses, although often through informal mechanisms. For the most part, they reported that they engaged in practices to limit co-witness discussion, although they also suggested that this can be difficult to achieve.