- "The evidence is in here. It's—it's in here. It's in all of us, every clone."
"What is it?"
"Organic chips built into our genetic code to make us do whatever someone wants, even kill the Jedi. It's all in here."
- ―Clone troopers Fives and Rex
Behavioral modification biochips, also known as inhibitor chips, control chips, and behavioral inhibitor biochips, were a type of organic bio-chip capable of dictating or responding to the thoughts of its host. Kaminoan cloners implanted them within each clone trooper in the Grand Army of the Republic at the third stage of their embryonic development. When they were activated the troopers responded to orders without question, allowing the Supreme Chancellor to initiate Order 66. The Galactic Empire later employed these devices to keep in line its enslaved Wookiee population on Kashyyyk.
Behavioral modification biochips had been implanted in the clone troopers to make them less aggressive than the clone template. They had been suggested by Jedi Master Sifo-Dyas, who initially ordered the clone army, as a contingency against the clones being given orders by rogue Jedi. According to Doctor Nala Se, it was not uncommon for clones of many different kinds to be implanted with inhibitor chips. However, after the Sith hijacked the project, the chips were also tooled to another purpose: to force the clones to comply with the execution of Order 66, which wiped out nearly all Jedi. The control chips were extremely effective at taking over the minds of people who had been implanted with them, erasing all existing biases and beliefs in the clone troopers to force them to eliminate the Jedi without question, even if the clones had loyally served under their Jedi General for years. The chips implanted inside the clone troopers could be activated by voice command, with Palpatine only needing to say "Execute Order 66" to do so.
Clone troopers under the sway of their control chips would prioritize carrying out Order 66 above all else, including their own lives. Although they could still make rational decisions, they could not be reasoned with regarding the order, and would unhesitatingly go after even their own brothers if they realized that other clones were not obeying the order. Brainwashed clones were also aware of Palpatine's true identity as the Sith Lord Darth Sidious, with clone officers who received the order immediately addressing him as "Lord Sidious" or "my lord," and clone troopers who had been completely unaware of the Supreme Chancellor's double identity beforehand referring to him by his Sith name. Pre-activation, the chips also had the side effect of giving the clones nightmares relating to carrying out the command. Clones under the sway of the chips occasionally used the phrase "Good soldiers follow orders."
It was possible in rare cases for some clones to resist the will of the chips and hesitate from executing the order, but the act was extremely difficult, and only removing the chip entirely could free a clone from the compulsion to carry out Order 66. Although extremely rare, a few clones were immune to the chips, with the odds being particularly high for genetically defective clones. Even if such clones were not immune, their mutations could still interfere with their chips' performance. In such cases, chips could be amplified to make clones totally loyal. Immunity, however, was not absolute: it was possible for the chip to be fully activated and induce brainwashing as long as it remained present, through means such as head injuries.
The chips were later installed in enslaved Wookiees by the Galactic Empire to keep them in line. Imperial Advisor Gallius Rax also had biochips installed in Rebel prisoners kept at Ashmead's Lock on Kashyyyk as part of an assassination plan against officials of the New Republic. When the chips were discovered, they malfunctioned in a planned degradation before Republic slicers could learn much about them.
- "I believe this is an organic chip built out of cells."
The biochips were, as the name indicated, made out of biological material, specifically genetically engineered cells. The DNA of the chips' cells was different from that of the clones they were implanted in. They were microscopic in size, and this combined with their biological nature made them extremely difficult to detect with standard medical equipment: it took a Level 5 atomic brain scan to find the chip inside the head of trooper Tup, after lower-level scans failed to register any anomaly. Ahsoka Tano was later unable to detect a chip with the standard medical facilities onboard a Venator-class Star Destroyer until she used the Force to locate it.
The chips were durable, with malfunctions being rare: out of the millions of clones that served in the Grand Army of the Republic over the course of the Clone Wars, Tup was one of only a few who suffered from chip malfunctions and the resulting erratic behavior. However, a chip malfunction could also prove lethal, as after Tup's chip malfunctioned, it broke down and began to rot, and his health began to deteriorate rapidly, culminating in his death shortly after the chip was removed. Damage to the inhibitor chip could result in headaches: Tup complained of a headache just before his chip went haywire, and the genetically defective clone Wrecker began suffering headaches connected to his chip after a series of head injuries sustained post-Order 66.
Creation of the clone army
- "You must remember the chip is a safeguard against betrayal from rogue Jedi. Master Sifo-Dyas was the only Jedi who knew of this. But with his passing, we alone know of this secret, and we must keep it that way."
- ―The disguised Count Dooku, to Lama Su
Prior to the Battle of Naboo, former Jedi Council member Jedi Master Sifo-Dyas contacted the Kaminoans to order a clone army for the Republic. He provided them with the inhibitor chip to make the clones less aggressive than the clone template and to act as a safeguard against betrayal from rogue Jedi. However, Sith Lords Darth Sidious and his new apprentice, Darth Tyranus, had Sifo-Dyas eliminated and took over his project, keeping it a secret from the Jedi. They retooled the chips for Order 66, programming them to turn the clones against the Jedi upon hearing an activation phrase. Kaminoans like Lama Su and Nala Se seemed to believe the chip was still only in case of rogue Jedi.
- "I already know this report's going to fall on deaf ears, but I owe it to Fives to record what I saw. I'm not sure I believe it myself, but there's a possibility that the inhibitor chips the Kaminoans put inside of us have a purpose that we don't yet fully understand."
- ―Clone Captain Rex's confidential grievance report on ARC trooper Fives' suspicions about the "inhibitor" chips
During the Clone Wars, the control chip conspiracy was nearly uncovered when the Order 66 function of the chip in clone trooper Tup was prematurely activated, causing him to execute Jedi General Tiplar during the Battle of Ringo Vinda. Though the Jedi discovered the existence of the control chips, they never learned of their true purpose, as the ARC trooper Fives, who had been investigating the matter, was killed by Clone Commander Fox of the Coruscant Guard. Afterwards, the official story was that Tup and Fives had both been infected with a rare Ringo Vindan parasite which caused their chips, supposedly there to keep the clones mentally stable, to break down.
Though Fives had warned that the conspiracy went to the highest level and that Supreme Chancellor Sheev Palpatine had tried to stop him from revealing what he knew, Anakin Skywalker stubbornly refused to believe that Palpatine was capable of what Fives was describing. Fives died in the arms of his friend Clone Captain Rex, whom he warned of the chips' existence and that the conspiracy was bigger than any of them. As he died, Fives' last words were that the "mission" and the "nightmares" were finally over. Due to Fives having been covertly drugged into a state of incoherency prior to his death, making him seem insane, Rex mostly did not believe his claims. However, he could not completely dismiss the possibility that the so-called "inhibitor" chips had a hidden purpose. Uncertain as to whether he believed it or not, out of loyalty to his friend, Rex filed a confidential grievance report in which he outlined the theory, although he was aware it was likely to be ignored. The Jedi High Council eventually discovered the Sith involvement in the clones' creation, but chose to keep it a secret, never making a connection between the discovery and the "inhibitor" chips.
501st Legion medic Kix, who had encountered Fives while he was on the run and who Fives had told he was being framed, eventually grew suspicious of the official explanation for Fives and Tup's behavior. At some point after the Battle of Anaxes, Kix, doing his own investigating, found out more than Fives had, including not only the true purpose of the chips but that Palpatine was himself a Sith Lord. However, he drew the attention of the Sith and was subsequently captured by Separatist forces sent by Count Dooku. His subsequent denials about sharing any of his knowledge failed to convince his captors, who placed him in a cryo-cycle stasis pod for transit to Serenno so Dooku could personally interrogate him. However, the cruiser Kix was being transported on, the Obrexta III, was attacked by Republic forces en route, subsequently crashing into the remote planet Ponemah.
- "It was at the end, the end of the war. Our fellow soldiers, the clones, the ones we Jedi fought side by side with, suddenly turned and betrayed us. I watched them kill my master. She fought beside them for years and they gunned her down in a second! Then they came for me. Later they said they had chips in their heads that made them do it. Said they had no choice."
- ―Kanan Jarrus describing what happened during Order 66 to his Padawan, Ezra Bridger
When Sidious executed Order 66, the chips worked as intended, with the overwhelming majority of the clone army brainwashed into obedience, resulting in the downfall of the Jedi Order and eventually, the end of the Clone Wars as a whole. The few exceptions included clones who had managed to remove their chips and the rare clones who were somehow immune.
Rex's knowledge ultimately saved his own life and that of Skywalker's former Padawan, Ahsoka Tano: at the end of the war, Rex, by that time having been promoted to Commander, was onboard the Venator-class Star Destroyer Tribunal en route from Mandalore to Coruscant. Having assisted the Mandalore resistance in winning the recent siege, Tano and Rex were delivering the captured rogue Sith Lord Maul to the Jedi Council. Tano had a vision of Skywalker's fall to the dark side and, only knowing something terrible had happened, ran to inform Rex. When he received Order 66 from Sidious, Rex realized that Fives had been right, managing to resist his chip long enough to tell Tano to "find" Fives before attacking her. During the short time he was brainwashed, Rex ordered some Coruscant Guard shock troopers to execute Maul, which they attempted to do before being stopped by Tano, who reluctantly released the Zabrak as a diversion. After escaping the initial assault, Tano was able to find Rex's grievance report, leading her to deduce what was going on before capturing Rex with the help of astromech droids to remove his chip, freeing him from the mind control. Maul subsequently brought down the Star Destroyer by destroying its hyperdrive; only he, Tano and Rex escaped the starship before it crashed. Afterwards, Tano and Rex went into hiding in the Outer Rim to escape the new Empire.
Most of the members of the irregular clone commando unit Clone Force 99–nicknamed the "Bad Batch"–were immune to Order 66 thanks to their genetic modifications. In the case of Echo, who was genetically a "reg" clone, Tech speculated that the experimentation he had undergone at the hands of the Techno Union in the aftermath of his capture at the Battle of Lola Sayu had broken whatever programming would have caused him to follow Order 66. However, CT-9904 "Crosshair" was the exception, with his inhibitor chip activating, although the effects were less evident than in normal clones. This led him to fire upon Jedi Commander Caleb Dume on Kaller when he and Clone Sergeant Hunter followed Dume into the woods after the death of Jedi General Depa Billaba, making Hunter's attempts to help Dume come off as insincere. When the Bad Batch was later imprisoned on Kamino following a failed mission to Onderon, Admiral Wilhuff Tarkin had the effects of Crosshair's inhibitor chip amplified, removing what loyalty he had retained to his squad and making him totally obedient to the Empire. The rest of the Batch shortly escaped from Kamino after a confrontation with their brainwashed former comrade.
Age of the Empire
- "What's in your head is more dangerous than you can imagine. I've seen what happens when the chip activates, and I don't want to bury any more of our brothers. Trust me. It is not something you can control. I couldn't. It's a risk you do not want to take."
- ―Rex warns the Bad Batch about not having their chips removed
In the aftermath of Order 66, Rex traveled to Saleucami, where he had encountered the clone deserter Cut Lawquane during the war. Cut had been unaffected by the brainwashing due to not hearing Order 66, and Rex warned him and his wife Suu about the inhibitor chips and how they had made the clones turn on the Jedi. After Rex left, the next day the Lawquanes were visited by the Bad Batch, who were also acquainted with Cut, and he brought up the implants Rex had mentioned. When Omega, a young enhanced clone who had previously worked as Nala Se's medical assistant, suggested that Rex had meant the inhibitor chips, Hunter was surprised to learn that the programming Tech had theorized about was connected to a physical device, although Tech had already come to that conclusion.
Subsequently, Tech came to suspect that Crosshair's betrayal was entirely the result of his inhibitor chip, although Echo was shocked that the chips were capable of such a thing. Tech began constructing a scanner to investigate the activity of the Batch's inhibitor chips and check whether they were truly inoperable. However, Wrecker, the Batch's strongman, received a head injury during a crash-landing on the Ordo Moon which began giving him headaches in the area of his chip. Hunter took notice of Wrecker's complaints, and after taking another hit to the head during a mission on Corellia, Wrecker passed out and mumbled the first words of the "Good soldiers follow orders" catchphrase. He was insensate for some time as the rest of his squad and the smugglers Trace and Rafa Martez fought attacking police droids, but came to after Omega contacted him and helped fight off the droids, still himself for the time being.
Some time later, Rex tracked down the Batch after learning of their location from the Martezes. He was concerned when he saw Wrecker having a headache and learned that he had been having them frequently, subsequently becoming alarmed when he learned that none of the Batch had removed their chips. Tech had concluded that the chips were not a danger to them, but Rex warned him otherwise, saying that they had no firsthand knowledge of how the chips made clones lose control. Rex had the Batch meet him on the junk planet Bracca to use the medical bay of a wrecked Venator to remove their chips. After reaching the medical bay, Tech used his completed scanner to assess Wrecker, but in the process, the large clone's chip activated and he attacked the others, decrying them as traitors. Eventually, after Wrecker had cornered Omega, Rex managed to stun him from behind, and his chip was removed. After Wrecker had come around and was confirmed to be okay, the other members of the Batch had their chips removed, and Rex parted ways with them.
Several months after the end of the Clone Wars, Clone Commander Grey, who had formerly served under General Billaba, was able to overcome his control chip and realize that he and his men had somehow been mentally influenced to turn on Billaba and her Padawan, Dume. Grey had spent most of the time since the end of the war hunting Dume, who had survived after Billaba sacrificed herself so he could escape. Realizing that his men would not be able to overcome the brainwashing, Grey deliberately lowered the deflector shields on his ship, securing Dume's escape with his own death and that of his men when Dume's protectors, Janus Kasmir and Kleeve, shot the ship down. Dume, who later changed his name to Kanan Jarrus, never knew of Grey's role in his escape and harbored a distrust of clones that lasted for years. At some point, Jarrus found out about the existence of the inhibitor chips. Eventually, he and the other members of the Spectres were sent to Seelos by Ahsoka Tano to recruit Captain Rex, who had been living on the remote planet with fellow clones Wolffe and Gregor, who had also had their chips removed. Uneasy at being around clones, Jarrus told his Padawan, Ezra Bridger, about what had happened.
In 18 BBY, a former Jedi Padawan named Ferren Barr on the run from Inquisitors led by Sidious' current apprentice, Darth Vader, used the Force to activate the control chips of nearby Purge Troopers, as he had noticed they were newer clones who had not yet had their chips activated. As Barr had just revealed that the Inquisitors present were all former Jedi, this caused the troopers to open fire on them. In the ensuing gunfight, the Inquisitor Tenth Brother was killed.
Once the Galactic Empire gained control of the galaxy, it enslaved the Wookiee population of Kashyyyk. Enslaved Wookiees were implanted with inhibitor chips which could be used to cause them extreme pain should they rebel against their captors. The chip could be activated in a rebelling Wookiee, causing pain until the Wookiee either fell back in line or died from the pain. As the Empire became more savvy, a common tactic was to instead subject family or clan members to pain, as the Wookiees would often be willing to sacrifice their own lives but couldn't bear to see the suffering of clan or family members. During the liberation of Kashyyyk, a strike team led by Han Solo disabled the field controlling the inhibitor chips, effectively rendering them useless and allowing the Wookiees to strike freely, though this was met with an orbital bombardment by Star Destroyers from the Galactic Empire.
Ultimately, the Imperial occupiers were defeated when a small New Republic fleet led by Admiral Ackbar and Captain Wedge Antilles entered the Kashyyyk system and forced their surrender. Wookiee Chewbacca's son Lumpawaroo likened the inhibitor chips to a song which sounded like the thrumming wings of a swarm of drriw-tcha blood-worm flies.
Rax also installed inorganic bio-chips in the brain stems of a hundred Rebel Alliance prisoners at Ashmead's Lock prison on Kashyyyk. These prisoners were part of a secret contingency plan to assassinate New Republic government officials and military commanders during the Liberation Day celebrations on Chandrila in 5 ABY. Rax and his undercover agent Windom Traducier used a transponder installed at the Hanna City opera house to transmit signals which activated the agents.
Prisoners installed with the bio-chips included Brentin Lore Wexley, Jonda Jae-Talwar, and Esdo. The unwilling assassins killed several New Republic officials and commanders, including Hostis Ij, but failed to kill Chancellor Mon Mothma. The New Republic authorities managed to subdue the prisoners. Investigations by the New Republic Security Bureau and the slicer Conder Kyl uncovered the chips. However, they malfunctioned as some kind of planned degradation before the New Republic could conduct further investigations.
New Republic Era
Around fifty years after the end of the Clone Wars, the wreckage of the Obrexta III was discovered on Ponemah after an ionic storm recharged the ship's distress beacon. Over the decades, the ship had acquired a mythical reputation as having carried a treasure of great value to Count Dooku. Since Dooku had been the wealthiest man in the galaxy prior to his death, the wreck attracted many bands of pirates willing to venture into Ponemah's dangerous Sea of Sand to find the Obrexta III and claim its alleged valuables. The Race for the Lost Treasure of Count Dooku was eventually won by the crew of Sidon Ithano; however, they instead discovered Kix, who had been kept alive inside his stasis pod for all that time. Ithano had the rest of his crew escape with the delirious clone, staying behind to what seemed his death as a giant sand worm destroyed the wreckage. However, he survived and rejoined his crew with the Obrexta III's memory core, which contained the location of every Separatist base in the galaxy, including some that remained undisturbed. Kix told his story to the pirates, including his doomed attempt to reveal the truth of the chips to the Republic and Jedi. As he had nowhere else to go, he joined Ithano's crew.
Behind the scenes
Control chips first appeared in the Star Wars: The Clone Wars episode "Conspiracy," of the "Orders" arc of The Lost Missions season. They were first referred to as control chips in the Star Wars Rebels episode "The Lost Commanders," and first identified as behavioral modification biochips in the tenth issue of the magazine Star Wars Helmet Collection.