Q: What's the difference between SHALL ISSUE and MAY ISSUE?
A: May Issue
A may-issue jurisdiction, within the context of gun law, is one that requires a permit to carry a concealed handgun, and where the granting of such permits is partially at the discretion of local authorities (frequently the police): the law typically states that a granting authority may-issue a permit if various criteria are met. A jurisdiction that is de jure a may-issue region may de facto range anywhere from no-issue to shall-issue.
Shall Issue
A shall-issue jurisdiction, within the context of gun law, is one that requires a permit to carry a concealed handgun, but where the granting of such permits is subject only to meeting certain criteria laid out in the law; the granting authority has no discretion in the awarding of the permits. Such laws typically state that a granting authority shall-issue a permit if the criteria are met, as opposed to laws where the authority may-issue a permit at their discretion.
Please understand this is just a guide. Being that a law can change faster than we can update, it is your responsibility to double check with your local law enforcement.