|The following article has no references to the official sources.|
The Gates of Justice are three massive structures that are each located at the World Government's three primary strongholds in the first half of the Grand Line; the judicial island Enies Lobby, the underwater prison Impel Down, and the now former Marine Headquarters Marineford.
They resemble large gates built into the air with the symbol of the World Government on them.
The three government facilities where these gates are located form a triangle. The water currents within this triangle that are redirected by the Gates of Justice form a gigantic spiral ocean current called the Tarai Current. By riding this current, ships are able to travel between these three locations at much greater speed than they would normally be able to.
When the gates are open, the current is let in and any ship can enter or exit the Tarai current with ease. However trying to sail in or out of the Tarai current directly is impossible, as the currents won't allow it. Additionally, if the gate at the destination is closed, then the ship would be unable to leave the Tarai current and would simply be forced forced to pass on by the location.
The purpose of these gates is to allow easy travel for Marine and Government ships between the three respective places they are located at. Thus, only ships affiliated with the World Government are allowed to pass through the gates. If criminals somehow managed to pass through the gates, they would most likely be trapped, since the World Government would refuse to open the gates again for the criminals and they would have no way of escaping the Tarai current.
Enies Lobby Gate
The gate in Enies Lobby is located at the very back of the judiciary island and is considered the final location. Once a person passes beyond the gate, the only two places they can go to are Marineford or Impel Down. Once a criminal passes through the gates, there is said to be no hope left for them; which largely held true until Luffy escaped Impel Down together with another 240 prisoners.
When the gate is closed, massive whirlpools are formed behind the Tower of Justice due to the current of the waterfalls surrounding the island. This creates an area that no ship can maneuver. For regular standard sized ships to pass through, the gate only need be opened a little bit. However since the whirlpools will continue to turn even if the gate only opens just a little bit, travel is still inaccessible. To solve this, an underwater tunnel was built that goes from the Tower of Justice, under the whirlpools, to a structure located in the middle of the gate, the Bridge of Hesitation. Once the gate opened up a little bit and the bridge is up, one can go to a pier located at the other side and ride the current.
However in order to safely go directly to and from the island, the gates must be fully opened so the whirlpools can be ceased.
Impel Down Gate
The gate of Impel Down is located on the border edge of the Calm Belt, so unlike Enies Lobby's gate, there is no current to prevent entrance towards the gates. However, to compensate for this, the Sea Kings that infest the area would attack any ship that is not coated with Seastone-hulls. The controls of the gates are located inside the generator room of the first floor.
Aside from being one of the three gates, little else is known about the one at Marineford. The Marines were refusing to open it for Monkey D. Luffy and his comrades. However, because Laffitte had hypnotized the guards to open the gates for anyone who approaches, Luffy's group has managed to leave the Tarai current the exact moment that Whitebeard and his allies arrived to rescue Portgas D. Ace.
- Monkey D. Luffy has visited all three of the three places that the Gates of Justice are linked to: Enies Lobby, Impel Down and Marineford. Also, he has caused significant damage to all three places; Enies Lobby was destroyed by the Buster Call, Impel Down suffered a mass breakout and considerable damage to the front gate, and though Marineford's breakdown was from Whitebeard's earthquakes, Luffy was also somewhat responsible for causing some damage by attacking the soldiers and crashing a ship into the sea.
- The Buster Call on Enies Lobby reached its destination after 30 minutes, and Gloriosa states that one can reach Impel Down from Amazon Lily in one week without the Tarai Current and in 4 days with. These facts suggest that one can travel 3 days worth of distance in half an hour when using the gates.
- One Piece Manga and Anime — Vol. 53 Chapter 522 (p. 10-11) and Episode 416, Elder Nyon explains a current that connects the three central government institutions.
- One Piece Manga and Anime — Vol. 59 Chapter 576 and Episode 485, Laffitte reveals that he hypnotized Marines who were at the control room of the Gates of Justice.