When choosing an armor plate for a police force, the main question to consider is, how often does a policeman gets exposed to rifle fire and armor piercing bullets?
Police do not wear armor plates on daily basis, in rare cases when police is after a terrorists or bank robbers with assault rifles, or when they in zone that is in an ongoing war and the police required to help to protect the checkpoints in and out of its territory only than they may wear armor plates for additional protection.
A law enforcement officer who goes about the day responding to crimes like domestic violence, routine traffic stops, responding to an emergency situation or simply cruising around the streets checking for small time thieves, burglars or drug dealers. Activities like this requires full mobility and comfort.
Usually police force using bulletproof vest with ballistic rating of IIIA that protect against handgun fire as 9mm and .44 mag. Most street battles are carried out with handguns that the level IIIA protection can handle. In the rare event that an officer encounters attackers who are using some high caliber weapons; specially trained and properly equipped officers like the SWAT team will handle such criminals, in this cases hard armor plates required because the daily soft armor will not be enough.
The level IV armor protection is meant to provide cover for armor piercing bullets, but level III (3) hard armor plate can provide almost same protection as the level IV (4) plate. And in most SWAT cases level III can provide the needed protection.
The level III protection is just the ideal type of bulletproof protection that any police officer needs as it enables good movement as level III armor plate come in 0.5-1KG less weight than the IV plate, also light plates as Polyethylene not come on level IV for reasonable price.
The level III armor plates have a few advantage over level IV ballistic materials because the level IV armor protection consists of materials that are very much costlier to buy, expensive to replace and heavier than a level III armor. This raises some concerns and leads to some questions. Why do we spend money to buy only one level IV protection when in some cases the same amount could be used to purchase two level III ceramic plates, especially when you order online and the shipping increases with the level IV plate as it is heavier.
Especially in the face to fact combat the level IV armor protection will be rarely needed. A heavy armor will also affect the mobility of a police officer. There are instances where a police officer will have to chase down a suspect. In some other cases, a police officer might need to engage the suspect in a physical combat before the suspect can be taking into custody. All of this makes this ceramic bulletproof plates with level III, the perfect choice for police officers.