Possible Clues:

• They may be human: Abbr.
• ABA issues
• Some offensive linemen: Abbr.
• Amendment concerns, briefly
• They may be human or civil: Abbr.
• Liberation movement issues: Abbr.
• Offensive NFLers
• Some NFL guards' neighbors
• Football linemen, for short, caught in 17-, 28-, 47- and 63-Across?
• ACLU interests