Spit guards, also known as spit hoods or spit masks (and occasionally bite guards) are devices intended to cover the mouth, face and sometimes the head of a restrained person in order to prevent them spitting at, or biting others. There is substantial controversy about their use with views often polarised between civil and human rights campaigners who express concerns about their utility, their safety, and their possible encroachment on human rights, and in contrast by (predominantly) law enforcement campaigners highlighting concerns about the possible risks of transmission of infection and subsequent need for prophylaxis by law enforcement professionals exposed to biological fluids. This study explored the extent to which police services deploy spit guards and the rationale underpinning their use. A mixed qualitative and quantitative approach was used to analyse data obtained from police services under the Freedom of Information Act. This study shows there is paucity of information readily available from police services in respect of quantifying the numbers of police officers who have contracted infectious disease as a result of spitting and/or bites, despite the fact that risk of infection and the need for subsequent prophylaxis is a driver of police services adopting the use of spit guard devices. Consideration must be afforded to the possibility that the use of spit guards represents a form of mechanical restraint rather than a means to prevent transmission of infection, especially given the paucity of information available from police services in respect of officers who have contracted infectious disease as a result of spiting and/or bites.