The Improper Use of Magic Office is responsible for investigating offences under the Decree for the Reasonable Restriction of Underage Sorcery and the International Confederation of Wizards' Statute of Secrecy. They regulate an under-age wizard's or witch's use of magic and prohibit wizards and witches from performing magic in the presence of Muggles or in a Muggle-inhabited area in the "Harry Potter" universe. An enchantment called "the Trace" is placed upon children and helps the department detect offences; it breaks when they reach the age of 17. However, Dumbledore explains to Harry that the Ministry cannot tell who exactly uses magic in a given area, only that it has been used. This can be seen as unfair to young witches and wizards who grew up in the muggle-world (such as muggle born wizards or those with one magical and one muggle-parent) as they are more likely to be caught using magic than those who grow up in the wizard world. Those living in the muggle-world generally have no contact with other witches or wizards away from school and the Ministry simply presumes that any magic performed where they are is an act of under-age wizardry, while at the same time presuming that any magic performed in a wizard home that has minors present was performed by those aged 17 and over. This means that minors living in the wizard world have a much greater chance of escaping punishment for the use of under-age magic. The Ministry has to rely on wizard and witch parents to enforce the ban on under-age magic within their homes.