An association football (soccer) match is presided over by a referee, whom the Laws of the Game give full authority to enforce the Laws of the Game in connection with the match to which he has been appointed (Law 5). The referee is oftentimes assisted by two assistant referees, and sometimes by a fourth official.
Barfoed's test. Barfoed's test is a chemical test used for detecting the presence of monosaccharides. It is based on the reduction of copper(II) acetate to copper(I) oxide (Cu2O), which forms a brick-red precipitate.
Breathalyzer tests are the most common devices used for detecting Blood Alcohol Content. They work by estimating BAC from a breath sample and are utilized mostly by law enforcement in conjunction with a field sobriety test. Police use these two means together to determine whether a driver has been drinking.