http://www.buckeyefirearms.org/node/8510
The above link is a memo from the Cincinnati police chief advising his staff about open carry in Ohio. There is a similar type of document in Michigan from the attorney general.
"Many people worry when they see someone openly carrying a gun. Officers can expect to receive calls when this happens. But, openly carrying a firearm, by itself, is not illegal. The fact that someone has called 911 or flagged down an officer about seeing someone with a gun in public is probably not enough to support an investigative detention. In such situations, an officer must observe the subject and evaluate the totality of circumstances to determine whether reasonable suspicion exists to justify detaining the individual. If the individual is doing nothing else that arouses suspicion, simply wearing a gun will not justify a detention.
"It is important to note, open carry by itself also would not support a charge of Disorderly Conduct or Inducing Panic. There must be additional facts to support these offenses. If someone is lawfully carrying a firearm—and doing nothing else— the fact that it causes alarm to others does not support a charge.
"Equally important, before you charge someone with a violation of Ohio Revised Code (ORC) 2921.29, Failure to Disclose Personal Information (also referred to as the "Stop and I.D." law), you first must have reasonable suspicion that person has, is, or is about to commit a criminal offense. The "Stop and I.D." law does not apply unless you already have a valid investigative detention of the person – and open carry by itself is not enough. Citizens may ignore your request for information during a consensual encounter, so you may only charge a citizen with a violation of ORC 2921.29 when they are legally detained.