This law is called Double Jeopardy.
Although this may seem beneficial and fair, it also has several disadvantages. The law is beneficial to innocent people, because it prevents them from being tried twice for the same crime, so they can not be acquitted and then later found guilty. However, this is also a disadvantage in some cases. In the past, there have been some court cases in which the defendant was acquitted, but later admitted to the crime. Because of the Double Jeopardy law, these people could not be found guilty and still have not received a punishment.
