The Klingons used a gavel with a large, outstretched arm, and their version of the tool was a metal ball. Courtrooms located on Qo'noS and Narendra III from the 22nd century to at least the 23rd century had this type of gavel. Klingon gavels emitted sparks upon hitting. (ENT: "Judgment"; Star Trek VI: The Undiscovered Country)
Adam – one of multiple disciples of Dr. Sevrin, who were brought aboard the USS Enterprise in 2269 – sang a song that contained the word "gavel" upon Captain James T. Kirk refusing to release Sevrin from medical confinement (since he was a carrier of synthococcus novae). The lyrics Adam sang were, "Stiff man putting my mind in jail. And the judge bang the gavel and say, 'No bail.' Gonna lick his hand and wag my tail." (TOS: "The Way to Eden")
Captain Kirk had a more concrete encounter with a gavel in 2293, as, in that year, one was used by an albino Klingon speaker, one of several hooded judges at Kirk and Dr. McCoy's trial on Qo'noS. (ENT: "Judgment"; Star Trek VI: The Undiscovered Country)
Gallery of gavelsEdit
Background information Edit
In the script for Star Trek VI, the judges' gavel in that film was described as "a grotesque mailed glove," mistaking the gavel for the glove that holds it. 
A concept drawing for the Star Trek VI gavel was created by Nilo Rodis-Jamero. (The Art of Star Trek, p. 267) Props master Gregory Jein carved the ball shape out of green foam, then had one of his employees in the props department cast the actual ball. Jein was aware of deviating from the red paint scheme commonly associated with the Klingons, opting to give the gavel a weathered steel finish. The prop was made so that streaks of light would burst out of the cracks in the gavel as it was struck. However, there was a difficulty with the gavel's interior light during filming. "The actor got too enthusiastic and the light broke on the second or third take," said Jein. (The Making of the Trek Films, 3rd ed., p. 128)
"Judgment" writer David A. Goodman was not entirely certain whether the sparks from the gavel in that installment were added in post-production or involved live pyrotechnics. However, he reckoned that at least some of the sparks were probably added after-the-fact, remarking, "I don't know that there's any way they could have done that live." ("Judgment" podcast/audio commentary)
A revised draft story outline for TOS: "Court Martial" (which had the working title "Court Martial at Star Base 811" and was dated 26 June 1966) stated that, during the court martial of James T. Kirk in that episode, "An old ship's bell is used instead of a gavel." However, a gavel was mentioned once in the final draft and revised final draft of the same episode's teleplay, in which it was scripted to be used by Commodore Stone during Kirk's court martial at Starbase 11; Stone hammered the tool on his desk in response to Spock and McCoy hurrying into the courtroom with new evidence. However, no gavel is present in the final version of the episode, in which "an old ship's bell" is indeed used instead.
A gavel was also scripted to appear in TNG: "Devil's Due", to be used by Data while acting as arbiter of a trial to determine whether an apparently non-corporeal lifeform was Ardra, but no gavel appears in that episode's final version either.  Similarly, the script for DS9: "Tribunal" mentioned a gavel though none is technically shown in that installment, with the episode's teleplay specifying that Makbar uses "not a gavel but a symbolic rock."