This is an example of a question that you might be asked during an oral board. Legally, you are able to let another officer process the suspect from a DUI arrest. Unless department policy prohibits this, it would be fine. Many neighboring departments can handle each others' calls when requested. Often, a neighboring department would respond to the robbery call and handle it until you could unload your DUI suspect or until a detective or another officer from your department could respond. Again, this depends on department policy.