Decree for the Reasonable Restriction of Underage Sorcery

"Dear Mr. Potter, We have received intelligence that you performed the Patronus Charm at twenty-three minutes past nine this evening in a Muggle-inhabited area and in the presence of a Muggle."

- Mafalda Hopkirk's letter adressed to Harry Potter on 2 August, 1995.

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 recognise that they may have to use magic in certain situations such as self-defence in a life-threatening situation. In addition, young children of 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
"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

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.

Also, 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.

Undetected breaches

 * Harry Potter performed the Wand-Lighting Charm shortly after his illegal usage of the Patronus Charm and letter, it did not add to his offense.
 * Tom Riddle, at age 16 during his summer vacation, used the Stunning Spell to incapacitate his maternal uncle, and then took his wand for multitude of uses: the Unlocking Charm to break into the Riddle House, the Killing Curse to murder his paternal family, and then to implant a false memory into his uncle to frame him. The Ministry did not even account Tom into the multiple breaches, let alone crimes, due to his uncle was in the vicinity, who instead became the suspect for every magic performed.
 * Bellatrix Lestrange trained her nephew Draco Malfoy in various fields of magic, which would most likely require Draco himself to use magic, during his summer vacation at age 16. Due to Draco being raised in a magical household, with both his mother and aunt being adult witches (albeit the latter being a wanted criminal), Draco's breaches could not be detected.
 * When Harry Potter was caught in the Battle of the Seven Potters, he used several spells to retaliate against the Death Eaters, such as the Disarming and Mending Charms. The Ministry ignored this breach due to wanting to keep the Azkaban breakout a secret.
 * Before Sirius Black defected from his family at age 16, he used the Permanent Sticking Charm to stick some muggle pictures of girls in his room. His breach was not detected due to his household being a magical family.

Behind the scenes

 * In the film adaptation of Harry Potter and the Chamber of Secrets, it is Hermione Granger who magically repairs Harry's glasses at Diagon Alley, not Arthur Weasley, which should be a violation of this decree. However, because the only Muggles around were those aware of the Magical Community and she was accompanied by two adults, Hermione was not punished.
 * In the film version of Harry Potter and the Chamber of Secrets Harry did not receive a warning for the illegal use of a Hover Charm which caused a continuity error with the following films due to the fact that the book version caused the Dursley family to learn that Harry cannot use magic outside of school.
 * The film version of Harry Potter and the Prisoner of Azkaban has Harry using the spell Lumos Maxima and yet receiving no warning. It is also possible Lumos Maxima was considered too mundane to be monitored; moreover, it was not performed in front of Muggles.

Appearances

 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Chamber of Secrets (film)
 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Prisoner of Azkaban (film)
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * The Tales of Beedle the Bard