Decree of the Reasonable Restriction of Underage Sorcery

The Decree for the Reasonable Restriction of Underage Sorcery is a bylaw of the Ministry of Magic, written in 1875, which bans the use of underage magic outside of school.

The Decree is enforced by the Improper Use of Magic Office in the Ministry of Magic. The restriction is for wizards and witches who are under the age of seventeen, upon which The Trace still operates. Even so, the Ministry does recognize that they may have to use magic in certain situations such as self-defense in a life-threatening situation.

In addition, young children below school age, or children who are not in possession of a wand, are mostly exempt from the rule since they usually have little or no control over the magic they perform. Overall, it appears the Ministry of Magic generally limits enforcement of the decree to situations where underage wizards perform magic in front of Muggles.

Known Contents
Paragraph C of the clause states that it is a crime to knowingly perform magic in a Muggle-inhabited area and in the presence of a Muggle. However, Clause 7 also states that magic can be used in front of Muggles in exceptional circumstances, including situations when the life of the witch or wizard is threatened, or the lives of other witches, wizards and Muggles are threatened.
 * "In the matter of Harry Potter, the law clearly states that magic can be used before Muggles in life-threatening situations."
 * —Albus Dumbledore at Harry Potter's hearing

It seems that a high-authority person may give permission for an underage student to perform magic under circumstances; as Hogwarts Headmaster, Albus Dumbledore gave Harry Potter such an instruction if an attack was to eventuate when he was 16 years old. Also, if an underage student unintentionally performed magic out of emotional stress, the Ministry may consider this to be accidental magic, and not punish said student, as Dumbledore noted that even the best of adult wizards cannot always control their emotions,[1] and Fudge did somewhat take this into account when he spoke to Harry about it.

The use of objects already enchanted by someone else does not count as a violation, as stated by Ronald Weasley, at that time aged 12, when he and his brothers Fred and George, aged 14, used their father's flying Ford Anglia during the summer holidays.