Specifically, with regard to the state of Wisconsin:
Chapter 167. Safeguards of persons and property.
167.31 Safe use and transportation of firearms and bows.
[definitions omitted]
167.31(2)
(2) Prohibitions; motorboats and vehicles; highways and roadways.
167.31(2)(a)
(a) Except as provided in sub. (4), no person may place, possess or transport a firearm, bow or crossbow in or on a motorboat with the motor running, unless the firearm is unloaded or unless the bow or crossbow is unstrung or is enclosed in a carrying case.
167.31(2)(b)
(b) Except as provided in sub. (4), no person may place, possess or transport a firearm, bow or crossbow in or on a vehicle, unless the firearm is unloaded and encased or unless the bow or crossbow is unstrung or is enclosed in a carrying case.
So let's skip to sub. (4) and see what the exceptions are, shall we?
167.31(4)
(4) Exceptions.
167.31(4)(a)
(a) Subsections (2) and (3) do not apply to any of the following who, in the line of duty, place, possess, transport, load or discharge a firearm in, on or from a vehicle, motorboat or aircraft or discharge a firearm from or across a highway or within 50 feet of the center of a roadway:
167.31(4)(a)2.
2. A member of the U.S. armed forces.
167.31(4)(a)3.
3. A member of the national guard.
167.31(4)(a)4.
4. A private security person who meets all of the following requirements:
167.31(4)(a)4.a.
a. He or she holds either a private detective license issued under s. 440.26 (2) (a) 2. or a private security permit issued under s. 440.26 (5).
167.31(4)(a)4.b.
b. He or she holds a certificate of proficiency to carry a firearm issued by the department of regulation and licensing.
My question would be what 'certificate of proficiency' is referred to. Does WI issue such?