How do line calls work, and who gets the benefit of the doubt?

From section 8 of the 2026 rulebook:

• You make the "out" calls for all lines on your end of the court. In doubles, either partner may make the call.
• Benefit of the doubt goes to the opponent. Any ball that cannot be promptly called "out" must be considered "in", and you must not call "out" unless you can clearly see a space between the line and the ball when it lands.
• Signal "out" promptly by voice, hand signal or both. A line call makes the ball dead.
• A served ball that lands on the non-volley zone line is "out".
• If doubles partners disagree, the team's call is "in".
• You may override your partner's call, your own call, or an "in" ruling to your own disadvantage.
• You may ask the opponent's opinion on a call you are responsible for, up until the next serve is hit. If they make a clear "in" or "out" decision, it stands.
• Spectators must not be consulted on any call.