Anna Phelan and Emily Adams wanted to end their four years at Bethesda-Chevy Chase High School with a memorable backyard graduation party. There was a blues band, a moon bounce, a popcorn machine and a pit for making s'mores. Guests feasted on hot dogs, hamburgers and bratwurst. There was plenty of ginger ale, cranberry juice and root beer to go around. What there wasn't plenty of was alcohol. "It was pretty low-key, and it was just sweet," Margaret Engel Adams, Emily's mother, said of the party for about 80 friends and relatives. "It was just pretty much out of Norman...