LogFAQs > #978848727

Dark_Arbron posted...

Those should be easy to circumvent for a sufficiently powerful wizard. Cedric Diggory was taken out in one shot by the death curse, and I dont believe he was over that age at the time.

Also if you have protection wards available why age restrict them? Unless theyre rolled in with the trace put on young wizards until the age you mentioned but that raises more questions.

It was a result of Lily sacrificing her life to save Harry. Petunia being her blood sister meant the protection extended to her home. What exactly this protection entails isn't specified beyond Voldemort being unable to touch him. It ended whenever Harry moved out or reached the age of majority.