Permits and Licenses
Public health agencies use permits and licenses to assure that businesses and individual who are going to engage in activities that affect the public health meet basic standards before they begin the activity, and that they continue to meet these standards as the activity progresses.  A permit is the right to do something once, such as the building permit for a new restaurant.  A license allows an ongoing activity, such as the license for running a restaurant once it has been constructed.  Permits and licenses are issued based on set criteria.  If you meet the standards, you get the permit or license.  This allows for planning by businesses because they know what standards they must meet.  This is much more efficient for the agency than allowing a business to open without review by the agency and only allowing the agency to close the business if it can prove it is not complying with the standards.
To get a license or permit you must agree to abide by the regulations of that business, to allow inspections of your business without notice or a warrant, and to keep records as required to show that you are in compliance with the appropriate rules.  For example, a restaurant is subject to inspection during normal business hours without a warrant.  If the restaurant does not allow the inspector to enter, then it can be closed.  Agencies have access to records that are maintained as a condition of the license or permit, without having to get a subpoena or court order.  This can be very important when tracing a food borne illness outbreak or a batch of bad prescription drugs.