"The truth must be won. I'll see you on the battlefield"
In 2372, Ch'Pok visited Deep Space 9 to serve as the prosecution in the extradition hearing of Lieutenant commander Worf, who commanded the USS Defiant during an incident in which a Klingon civilian transport ship was apparently destroyed, supposedly killing all 441 passengers and crew aboard. The incident was a ruse designed to embarrass the Federation and possibly take control of the Pentath system.
It was Ch'Pok's responsibility to "prove" that Worf was full of bloodlust and would knowingly attack an unarmed opponent. He questioned Jadzia Dax, Miles O'Brien and Benjamin Sisko to demonstrate his case. However, he also broke into Worf's personal database to show he was running a holoprogram, Battle of Tong Vey, in which the main character advocated attacks on children. Worf allowed the breach of privacy, since he had nothing to hide, but was slightly embarrassed when Dax confirmed the nature of the program. He pressed O'Brien on whether he, given command, would have fired on a decloaking ship without confirming its identity. He eventually said no, but he is also not able to put himself in the command chair. Finally, he infuriated Worf by accusing him of killing innocent people to prove himself a true Klingon. At first, Worf denied that he would do such a thing, but, angered and feeling that his honor had been questioned, he attacked Ch'Pok. Satisfied that he had proven his point, Ch'Pok rested his case in front of Admiral T'Lara.
The ship was later determined to have falsified its sensor readings in order to appear as though it had a full crew aboard when in fact it was empty; all of the supposed victims never existed. Sisko forced Ch'Pok to admit that the entire affair was staged in order to discredit Worf and was part of a elaborate Klingon plot to stop the Federation from escorting Cardassian freighters. (DS9: "Rules of Engagement")
"Worf is about to present us with something we never could have won in battle. Sympathy. Any move we make against you will be seen as a legitimate response to an outrageous slaughter."
- - Ch'Pok, to Benjamin Sisko
"We Klingons are not concerned with matters of fact and circumstance. What matters to us is what was in Worf's heart when he gave the order to fire. Was he just a Starfleet officer doing his duty or was he a Klingon warrior reveling in the battle? That is why I am here. Because if he was a Klingon lost in the bloodlust of combat, only we can judge him, not you."
- - Ch'Pok
"The names and faces of these people are seared into my heart. This is a list of heroes who died at the hands of a coward. It is a list I can never forget."
- - Ch'Pok
Ch'Pok was played by actor Ron Canada.
The script for "Rules of Engagement" gives the pronunciation of Ch'Pok's name as "chi-POK (rhymes with Reebok)"  In a deleted scene, Ch'Pok also requests that Worf remove his baldric as it is offensive to him, echoing Duras’ words when Worf challenges the High Council’s ruling against Mogh in "Sins of the Father". 
During filming of the episode, Canada became sick but continued to act the part of Ch'Pok while feeling unwell. "His role was very dialogue intensive," recalled Director LeVar Burton, "It was a superhuman effort on his part to get through it. He did a terrific job." (Star Trek: Deep Space Nine Companion, p.324)
Star Trek author Keith R.A. DeCandido liked the character of Ch'Pok, which he said was "well played" by actor Ron Canada, but criticized his logic. "It’s fun in the abstract to see a Klingon lawyer," wrote DeCandido, "but Ch’Pok comes across as spectacularly incompetent. He is making a case before a Vulcan admiral, and so chooses an emotional argument. He seems to be trying to get a rise out of Worf, but Worf isn’t the one making the decision, T'Lara is, and not a single point Ch’Pok makes speaks to logic or rule of law."