Sometimes called "paramedic shears," "EMT shears," or "tuff cuts," trauma shears are scissors designed to be used by those in emergency medicine. Typically, they will be used by paramedics and EMTs (Emergency Medical Technicians) to cut clothing off of patients, but they are also used in hospitals for removing cardboard splints and backboard webbing or tape from patients, can have applications in some surgical procedures, and are also often used by divers to cut through wire or netting.
The shears themselves have a rather unique design. The blades are flat rectangular pieces of stainless steel. The lower blades on most pairs have a ridged edge to grip what they are cutting into and some sort of angled flange or other special tip for lifting clothes off of patients' bodies. The tips of all pairs of shears are blunt or rounded to prevent accidentally injuring the patient. Both blades are angled 10-15 degrees from the handles, giving trauma shears their unique look. Handles are usually made of plastic with large holes, both to make them easy for anyone to grip and also to make it easy to attach them to a belt, bag, or special holster.
Though slightly clumsier than actual medical scissors, trauma shears are nonetheless very useful. While the typical medical scissors that people think of (small, rounded, metal scissors) are excellent for suturing or surgery, trauma shears can take on many things that medical scissors cannot. Their cutting power is almost unmatched--they will go through almost anything that their size can handle. They are frequently used for removing a patient's clothing when that patient cannot remove his/her own clothes (such as when the patient is strapped to a backboard or is unconscious), or for cutting seatbelts to remove patients from automobile accidents. Beyond their typical uses, I have personally used my pair to open those pesky sealed plastic packages new cell phones come in, and have even sliced a penny in half. Trauma.org recommends using them when splitting a sternum, and multiple dive web sites recommend divers carry them when visiting wrecks to help cut through microfilament line, netting, or steel leader. For those who are into escaping from police custody, trauma shears (or "snub nose cutters, as EZ Cuff calls them) are standard equipment for removing the plastic zip-tie restraints often used by riot police.
Trauma shears are available from almost any medical supply company, as well as bookstores that specialize in medicine (check your local medical school), uniforms and scrubs stores, outdoor supply companies such as NOLS, and even some dive shops. A pair typically costs a couple dollars, and can always be found in bulk for cheaper. They're standard equipment in most emergency rooms and with all EMTs and paramedics, and I would recommend them for any large (office or industrial) or wilderness first aid kit.