“No harm, no foul” (“No blood, no foul”)

“No harm, no foul,” in the game of basketball, means that a referee will ignore minor infractions off the ball, allowing rough contact between the players but keeping the game continuing with minimal stoppages.  “No harm, no foul” has been cited in print since at least 1954.
 
“No blood, no foul” means that a referee really doesn’t want to call anything, unless a player is seriously hurt. “No blood, no foul” has been cited in print since at least 1968.

Los Angeles Lakers sportscaster Chick Hearn (1916-2002) is often credited with coining “no harm, no foul,” but Hearn began calling Lakers games in 1965— over a decade after the term had first been used. It’s possible that Hearn first said “no blood, no foul,” but documentation is needed.
 
 
Wiktionary: no harm, no foul
Noun
no harm, no foul

1.Encapsulation of the idea that although technically a breach of some code or law may have occurred there is no need for punishment, apology or retribution if no actual damage occurred.
       
Wikipedia: Chick Hearn
Francis Dayle “Chick” Hearn (November 27, 1916 – August 5, 2002) was an American sportscaster. Known primarily as the long-time play-by-play announcer for the Los Angeles Lakers of the National Basketball Association, the legendary Hearn is remembered for his rapid fire, staccato broadcasting style, inventing colorful phrases such as slam dunk, air ball, and no harm, no foul that have become common basketball vernacular, and for broadcasting 3,338 consecutive Lakers games starting on November 21, 1965.
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Chickisms
The particular phrases that Chick used during his broadcasts were labeled “Chickisms”. Many are staples of basketball.
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No harm, no foul (no blood, no ambulance, no stitches): A non-call by an official when varying degrees of contact have occurred. (More adjectives means the non-call was more questionable.)
 
21 October 1954, Newport (RI) Daily News, pg. 12, col. 1: 
ANY ONE who ever played basketball will agree with Dr. H. C. Carlson, former University of Pittsburgh coach, that the non-contact theory is a myth. It is very difficult to avoid contact when 10 fast-moving players simultaneously, utilize only about one-eighth of the floor, he says.
 
Dr. Carlson lists three fouling categories—negligible, questionable and unquestionable. Negligible fouls can be ruled out, and thereby cut 30 per cent of whistle blowing. An example of such a foul is when a defensive man barely touches a backboard recovered or dribbler. There has been no real interference, no harm, except that play was stopped by the whistle.
   
All fouls carry the same penalty. In Dr. Carlson’s opinion, if the rule “no harm, no foul” were followed, a great game would be made greater. Dr. Carlson was the originator of the continuity or figure 8 attack.
 
Google News Archive
22 December 1954, Pittsburgh (PA) Post-Gazette, “Roamin’ Around” by Jack Sell, pg. 17, col. 1:
“It was unanimously agreed by the coaches in their meeting at Kansas City that the “no harm, no foul” rule was the finest for the game years,” Moore asserted.
(Coach Dudey Moore of Duquesne—ed.)
   
17 March 1955, Indiana (PA) Evening Gazette, pg. 24, col. 2: 
Enforcement of the no-harm, no-foul rule would also be a boon. Fouls which don’t affect the play, or are obviously unintentional, could easily be overlooked.
 
20 December 1956, Oshkosh (WI) Daily Northwestern, pg. 36, col. 1: 
The conference coaches also agreed that Big Ten officials this winter should emphasize a principle of “no harm, no foul.” Thus, fouls will not be called so frequently on incidental contact where ball control is not affected.
 
Google Books
24 Seconds to Shoot;
An informal history of the National Basketball Association

By Leonard Koppett
New York, NY: Macmillan
1968
Pg. 149:
Such an attitude promoted rough play, since it stressed to the utmost the “no harm, no foul” philosophy which quickly became, in the pro context, “no blood, no foul.”
 
31 March 1970, Morning Star (Rockford, IL), “SportScoop” by Steve james, pg. B1, col. 1:
With the NBA, under its present “no blood, no foul” policy, it’s no wonder players get upset. Anyone would have a difficult time understanding what is and what isn’t a professional basketball foul.
   
7 December 1976, New York (NY) Times, “A Grass-Roots Hockey League Groves in Brooklyn: Who Needs the Ice?” by John S. Radosta, pg. 86:
And then there are the local rules, similar to the “no blood, no foul” rules of playground basketball.
 
26 March 1977, Washington (DC) Post, “Final Four Officials Have Survived a Playoff of Their Own” by Mark Asher, pg. C4:
Added Steitz: “We want the game officiated in the spirit and intent of the rules, not the ultra-liberal interpretation of ‘No blood, no foul.’”