Every Wednesday, this site delves into a rule or governing principle that shapes how tennis is actually played. We are currently in the midst of a sequential walkthrough of each of the Principles that appear in “The Code,” which the USTA bills as “The Player’s Guide to Fair Play and the Unwritten Rules of Tennis.” This week, we are focusing on Principle 7, which is a part of the “Making Calls” section.
Ball touching any part of line is good. If any part of a ball touches a line, the ball is good. A ball 99% out is still 100% good. A player shall not call a ball out unless the player clearly sees space between where the ball hits and a line.
USTA Friend at Court 2025 , The Code, Principle 7 (Complete)
This is one of the few places where The Code abandons nuance. There is no sliding scale or compromise. Tennis calls are binary, meaning there are only two possible outcomes. The ball is either good or it is out. A ball cannot be mostly out or essentially out. If any part of the ball touches the line, it is in.
That reality often clashes with our human urge to approximate. A ball can land overwhelmingly outside the painted boundary and still clip the line by a millimeter. Even though it looks out, under the rules, it is unequivocally good. The phrase “A ball 99% out is still 100% good” is needed because human beings want to round in their own favor. Principle 7 explicitly prohibits that instinct.
It is worth noting that the final sentence in Principle 7, “A player shall not call a ball out unless the player clearly sees space between where the ball hits and a line,” did not appear in the 2001 version of The Code that we have been using throughout this series as a historical reference. While the first sentence makes it clear that a ball touching the line is good, it does not explicitly specify visible space between the ball and the line to make a call. That omission left room for interpretation.
The newer language closes that gap. It shifts the burden of proof. The question is no longer whether the ball was likely out, but rather whether the player clearly saw it out. Without that visual confirmation, the call cannot be made. It is a subtle, but significant shift.
The strength of the language is intentional. Anything softer would collapse under competitive pressure. Players are not permitted to call balls out based on vibes. That is not to imply that players routinely cheat. Rather, it acknowledges something more human. Vision is imperfect. Our eyes deceive us. Speed blurs perception. This part of The Code is written around those limitations.
Principle 7 is built for real-world tennis. It assumes human imperfections. That is precisely why it demands visible space before a ball can be called out. Without that requirement, calls potentially become pliable under pressure. By insisting on visible space, the rule removes approximation and narrows the gray area where disputes can arise.
If you clearly see separation, call it out. If you do not, play continues.
- Friend at Court: The Handbook of Tennis Rules and Regulations, USTA, 2025
- Friend at Court: The USTA Handbook of Tennis Rules and Regulations, USTA, 2001. (Hardcopy.)
For readers who may be new to the organized tennis landscape, the Friend at Court is the USTA’s compendium of all rules governing sanctioned play in the United States. It includes the ITF Rules of Tennis, USTA Regulations, and additional guidance specific to competition in this country. The Code is nested within the Friend at Court. That section outlines the “unwritten” traditions, expectations, and standards of conduct that guide player behavior. The Code is the ethical framework that shapes how recreational and competitive players conduct themselves every time they step onto the court.