Also seit 3E gilt das eigentlich nicht mehr. Seit 4E ist der Verhaltenskodex auch nicht mehr restriktiv.
Aus dem 3e PHB (p.43):
"Ex-Paladins
A paladin who ceases to be lawful good, who willfully commits an evil act, or who grossly violates the code of conduct loses all special abilities and spells, including the service of the paladin’s warhorse. She also may not progress in levels as a paladin. She regains her abilities if she atones for her violations (see the atonement spell description, page 176), as appropriate."
Aus dem 3.5 PHB (p. 44-45):
"Ex-Paladins
A paladin who ceases to be lawful good, who willfully commits an evil act, or who grossly violates the code of conduct loses all paladin spells and abilities (including the service of the paladin’s mount, but not weapon, armor, and shield proficiencies). She may not progress any farther in levels as a paladin. She regains her abilities and advancement potential if she atones for her violations (see the atonement spell description, page 201), as appropriate. Like a member of any other class, a paladin may be a multiclass character, but multiclass paladins face a special restriction. A paladin who gains a level in any class other than paladin may never again raise her paladin level, though she retains all her paladin abilities. The path of the paladin requires a constant heart. If a character adopts this class, she must pursue it to the exclusion of all other careers. Once she has turned off the path, she may never return."
Aus dem 4e PHB (p.90), markiert von mir:
"Paladins and Deities
As fervent crusaders in their chosen cause, paladins must choose a deity. Paladins choose a specific faith to serve, as well as an alignment. You must choose an alignment identical to the alignment of your patron deity; a paladin of a good deity must be good, a paladin of a lawful good deity must be lawful good, and a paladin of an unaligned deity must be unaligned. Evil and chaotic evil paladins do exist in the world, but they are almost always villains, not player characters. [...]
Once initiated, the paladin is a paladin forev-ermore. How justly, honorably, or compassionately the paladin wields those powers from that day forward is up to him, and paladins who stray too far from the tenets of their faith are punished by other members of the faithful."
Für die 5e zitiere ich mal aus DNDBeyond:
"Breaking your oath
[...] If a paladin willfully violates his or her oath and shows no sign of repentance, the consequences can be more serious. At the DM’s discretion, an impenitent paladin might be forced to abandon this class and adopt another, or perhaps to take the Oathbreaker paladin option that appears in the Dungeon Master’s Guide."
Die 4e ist hier also klarer Ausreißer und alle anderen Editionen erlegen dem Paladin einen Verhaltenskodex auf, dessen Bruch dazu führen kann, dass der Paladin kein Paladin mehr ist.
Oder hast du da andere Belegstellen im Kopf?