Many actions or inactions as it may be can end up leading to a criminal case. For example something like a physician performing a pelvic exam without a glove on could be a criminal case. Use of protective equipment such as gloves is put in place to protect both patient and doctor it would be a dangerous and reckless move not to wear them in such a setting.
There are actions that are unethical and may even stand to be punishable but are not considered criminal. For example if a doctor does not pay back their student loans this is not the right choice to make but it will not stand up as a criminal case.