Defender of Law

• WOTC Official Reminder Textofficial rules
  Protection — This permanent can't be damaged, enchanted, equipped, blocked, or targeted by [quality].
• WOTC Official Reminder Textofficial rules
  Flash — You may cast this spell any time you could cast an instant.

• WWizards of the Coast2004-10-04
  Official Ruling
  This card is always a creature spell and is never an instant spell, no matter when you cast it.

Rulings via Scryfall