Respecting the people you work with is key to a successful relationship. When I was "on the hook" for a project and someone didn't complete their quota, I did my best to present the situation it a way that made it a "help me help you" kind of thing. I have to tell my manager that you didn't do your part, so why don't you try to get this done? I don't want to look bad, and I don't want you to look bad.
All employees are subject to compliance rules and need to responsibly perform their job functions within acceptable parameters and their actions must be monitored for compliance issues. Corrective actions would be necessary corresponding in size or degree of the perceived violation.
In my career as an employee relations professional I have always found it best to remain calm, gather facts, consult both parties, and then do my best to make an unbiased judgement which will hopefully benefit both parties.