Law Enforcement Officers will be more than aware of the dangers they face daily, and the need for body armor. Over the last decade, there were nearly 60,000 assaults a year on Officers according to government statistics. Body armor is a necessity, clearly- but no two Officers are the same, and the dangers facing one Officer may be vastly different to those another Officer faces. This is why Law Enforcement Officers need to be aware of the different levels of protection available, and the different types of body armor available.
Bulletproof vests will be suitable for most Officers, as handguns make up the vast majority of weapons used in crimes committed in the USA. However, when working in an environment where guns are not likely to be encountered, or knives and stabbing weapons are simply more accessible, a stabproof vest will be required. It may be preferable to wear a multi-threat vest capable of dealing with both, to ensure complete protection. It is also important to make sure that the protection offered by the vest worn will match the ammunition used by the Officer. For most Officers, however, the real decision will be in deciding whether to wear a covert or overt vest.
Some Officers may favor a covert vest for several reasons; when working undercover, for example, it is important to still be protected without drawing attention to yourself as a Law Enforcement Officer. However, an overt vest is required for most, partly because there will be no need for a covert vest, but also to act as a deterrent to potential threats. Overt vests can also be worn as part of a uniform with departmental insignia, and manufacturers usually offer additional pouches and equipment to be worn specifically for Law Enforcement.
There will be certain members of Law Enforcement who deal specifically with high-risk and extreme situations, such as SWAT teams. When you are expecting to be involved in an extremely dangerous situation involving high-caliber weapons and ammunition, hard armor at Level III or IV is required. As mentioned elsewhere, this armor is naturally much bulkier and heavier than lower levels and will be uncomfortable when worn for extended periods. For SWAT teams, however, additional protection will also be required, including neck, head, and groin protection that easily supplements hard armor.
As well as research into lighter and thinner bullet-resistant materials, there is a focus on research into new materials altogether. Of particular significance for SWAT teams and Emergency Law Enforcement Responders is research into membranes for armor that can protect against CBRN (Chemical, Biological, Radiological, and Nuclear) threats. These materials are not yet mass-produced, but CBRN protection is already included in official Government information concerning standards of armor.