This video discusses factors affecting line call rules including the rule itself, court lines, compression of the ball and point of contact.
SECTION 6 – LINE CALL RULES
6.A. Served balls that clear the non-volley line and land on any other service court line are good.
6.B. Balls in play (except on serve, see 6.A) that land on any court line are good.
6.C. A ball contacting the playing surface outside of the baseline or sideline, even though the edge of the ball overlaps the line, is considered out of bounds. (revised April 1, 2011)
6.D. Code of Ethics for Line-Calling.
Pickleball is played according to specific rules. It also requires a code of ethics for line-calling responsibilities when performed by players. The line-calling responsibilities of players are different from those assigned to referees or line judges. The officials make impartial judgment calls with all players’ interests in mind. The player, when assigned line- calling duties, operates under the principle that all questionable calls must be resolved in favor of the opponent. The basic elements are:
6.D.1. Players will call the lines on their side of the court (excluding the non-volley line, if being called by a referee).
6.D.2. The opponent gets the benefit of the doubt on line calls made. Section 6: Line Call Rules 25
6.D.3. Spectators should not be consulted on any line calls. Spectators may be prejudiced, unqualified, or not in position to see the call, and therefore cannot participate.
6.D.4. All participants should strive for accuracy in making line calls.
6.D.5. No player should question an opponent’s call unless asked (except that any player may appeal a call to the referee in an officiated match). A player should ask the opponent’s opinion if the opponent was in a better position to see the call. An opponent’s opinion, if requested, should be accepted. The opinion of a player looking down the line is more likely to be accurate than one looking across the line.
6.D.6. Don’t call a ball “out” when you are looking across the line unless you can clearly see the space between the line and the ball as it hits. The player’s depth of field judgment, based on the laws of parallax, prevent accurate judgment in these cases.
6.D.7. All “let” or “out” calls must be made “instantly”; otherwise the ball is presumed good and still in play. “Instantly” is defined as calling “let” or “out” prior to the ball being hit by the opponent or before it has gone out of play.
INTERNATIONAL FEDERATION OF PICKLEBALL (IFP) OFFICIAL TOURNAMENT RULEBOOK
Last Revised: March 31, 2014
Source: Thanks to Alison and Doug Bailey