The safety standards for body armor vary from country to country, as many of the countries have their own specific tests and standards. However, in the world there are two major agencies; American NIJ (National Institute of Justice) and the UK HOSDB (Home Office Scientific Development Branch) are considered to be the model standards for ballistic and body armor, and most of the countries will consider the safety levels offered by a piece of body armor that is certified by either of these agencies.
In ballistic industry, NIJ is considered to be the leader in testing methods for body armor, and the HOSDB’s is considered best at stab and spike tests. Also, NIJ and the HOSDB work together with each other on their testing methods. It is accepted if a piece of body armor that passes NIJ standards will also pass the equivalent HOSDB standard.
Any Body armor like the bullet-resistant vest, hard armor plates or ballistic helmet is designed to give protection against 3 broad types of threats – bullet, stab, and spike. The design of the body armor decides the protection to be offered. For example, some type of body armor will provide protection from just ballistic threats, while others will provide protection against bullet and stab attacks.
Each body armor is labeled with the information that what kind of protection it provides. The higher the number on the protection, the higher the level of protection it will offer. For example, a bulletproof vest with level IIIa protection will provide a higher level of protection than a bulletproof vest with NIJ Level II protection.
As per NIJ, there are 6 main threat levels for ballistic body armor.
For soft body armor- Level I, Level IIA, Level II and Level IIIA. For hard armor (plates) Level III and Level IV which are designed to defeat projectiles at rifle speeds in conjunction with the soft body armor tested specifically for that combination.