Regulator (Fallout 3)

The Regulators are a group of self-appointed lawmen from the Capital Wasteland who wear cowboy style hats(Sheriff's Hats) and Regulator Dusters after the fashion of gunslingers, they operate out of a farmhouse, lead by Sonora Cruz. If the player has the Lawbringer perk, he/she can trade fingers taken from the corpses of evil humans killed by the player, for good karma and Bottlecaps. The Regulators will also attempt to claim the bounty on the player's head if he or she commits serious crimes, such as destroying Megaton or enslaving people in the Capital Wasteland.

Overview
Regulators wear Regulator Dusters, and seem to have a fondness for laser weapons (Laser Pistols and Laser Rifles) although more commonly they have Combat Shotguns, Chinese Assault Rifles and Combat Knifes. In terms of durability and combat challenge, they're about equal to a Talon Company Merc (although with severely less protective armor). Regulator patrols typically operate in 3-man squads when searching the Wasteland for the player character if that player is evil or very evil. They are very deadly and effective at close range(if they have Laser Rifles, long range)and it would be wise to take out the one with the longest range weapon first and then backpedal(whilst firing) to some cover and take potshots at the one with the Combat Knife or Combat Shotgun.

If you have the Lawbringer perk, a Dead Regulator will be found outside of the entrance to Arlington/Wasteland Metro in Arlington Cemetery North. He will have a bounty note for Junders Plunkett. It says he was last seen in Canterbury Commons, but really he is in the nearby Arlington House. You can kill him and take his finger. It is worth 1,000 caps back at the Regulator HQ.

Bugs

 * There is a bug where a player can pick-pocket a regulator, and he/she will have a named bounty for the player on them, even if the player is completely good.
 * Sometimes if the character fast-travels to the Regulator HQ, a giant radscorpion will be attacking the brahmin outside. If the character enters the HQ without killing the scorpion, Sonora Cruz can run out of the HQ into the wasteland and sometimes be found ontop of a hill next to the scrapyard just southwest of the regulator HQ or on a hill overlooking the Wheaton Armory. Any attempt to talk to her will result in 'Sonora Cruz is fleeing' and she will continue to crouch and stand up, directly across from a large Raider base. (Wheaton Armory bug). If Sonora is neither near the Armory or hilltops next to, stand in front of the Regulator HQ and look DIRECTLY east, head straight  the easterly direction, and she should pop into view just as you start moving towards the collapsed bridge. Look specifically at the pile of rubble gathered near the second bridge support column on the left, Sonora should be there.
 * Note that the Regulators will target you if your Karma ever goes to "evil". Even if your karma dips to evil (i.e. if you enslave a few Raiders using the Mesmetron), and you quickly get it back up to "good" (i.e. by giving purified water to beggars) without encountering the Regulators, you will eventually encounter hostile Regulators even as a "good" character. Sometimes, a squad of 3 Regulators will even appear alongside a squad of 3 Talon Company Mercs to fight you! Ironically, they usually start fighting each other when you encountered both of them. These Regulators also carry bounty notices against you.
 * There is a bug, on all three versions, that Sonora Cruz will 'flee' from you if you approach her for no reason regardless of having good Karma. If you DO approach her she will run from the Regulator HQ and then you will see a message "Sonora Cruz is unconscious" (as an NPC she'll be easily picked off by the large animals or Enclave troops in the area). Returning to Regulator HQ after this finds her gone and nothing to do with your growing collection of fingers. It seems that this "bug" happens when you enter the HQ after being spotted by hostile NPC. To prevent this from happening, "sneak" before entering the HQ, if you are "HIDDEN", you can enter safely, otherwise you will need to take care of the hostiles (probably giant radscorpions)
 * This bug seems to occur more frequently when approaching with a drawn weapon.
 * Junders Plunkett's body had both a normal finger and Junders Plunkett's Finger on his body. If you try to turn both fingers in to Sonora Cruz at Regulator HQ for the normal and special bounties. The named finger remains in your inventory.
 * After you are able to make James Hargrave runaway from Rivet City, he will end up with C.J. Young at the Anacostia Crossing Station. If you have bad karma and have not encounter the Regulators before, they may show up at the Anacostia Crossing Station if you walk near it and begin attacking James Hargrave and C.J. Young. The poor children are assaulted, and the Regulators won't attack you until you first have had a conversation with one of the Regulators.

Appearances in games
Sonora's Regulators appear only in Fallout 3. It must be noted that these Regulators are NOT affiliated in any way with Caleb's Regulators in Fallout 1. They share absolutely nothing in common other than, out of pure coincidence (and some irony), the same name.