By entering any competition in D3CL you agree to follow these rules.
Patch 2.0.6. Ruleversion 1.0

General Rules

• The legit pvp rules are: Fair play and good manners.
• Before each match please perform the legit test procedure. The test procedure can be found HERE. The legit test procedure is impelented to assure players protection against breaking the rules, such as gear swapping, macros or banned spell.
• Duels are held in 'Inferno' difficulty in normal D3CL league and in 'Normal' difficulty in low level dueling D3CL league.
• Duels are played with best of 9.
• Maximum duel time is 45 minutes starting from the first ‘go’ from both sides.
• The small island inside the scorched chapel area is forbidden ground. Actively using this island will result in loss of rounds and/or the complete match.
• You cannot enter town or leave the game during a round, if that happens the person who enters town or leaves the game looses the round.
• If a player wish to change Equipment between rounds he has to announce it to the other player. Both players will then travel to town and once more agree on Equipment for the duel. If nothing is said to be changed a travel to town, or a new agreement about equipment is not necessary.
• We expect the duels to be active combat. Repeatingly avoiding the duel will result in a loss.
• Vanishing Dye is not allowed.
• Round(s) resulting in a draw (both players kill each other) counts as +1 round for player, who killed his opponent first.
• The winner of the duel must stay in screen from opponent once won.
• You must play your duels using the character you signed up with for the League or Tournament.
• The judge may limit the field of play if the fight is prolonged.

One Vs One (High Level)

• No class specific balancing rules.

Two Vs Two (High Level)

• Class specefic rules do not apply here!
• You are not allowed to team up with an equivalent class.

One Vs One (Low Level Dueling)

• General rules apply.
• Hellfire ring, The Horadric Hamburgers and Spectrum are forbidden.
• You may only use up to Flawless Square gems in your socketed gear.
• No life % regeneration passives allowed (“Broodling” for Demon Hunter, “Inspiring Presence” for Barbarian and “Blood Magic” for Witch Doctor).
• Monks are not allowed to use Breath of Heaven.
• Witch Doctors may only use “Hex” or “Horrify”, not both at the same time.
• Max 50 life regeneration from items.
• Healing potions are forbidden.

Based on the d2jsp LLD rules.

Penalties

• Any minor rule break result in one lost round, and +1 to the enemy. A minor rulebreak is something that can be understood as a human mistake. Like sorry I forgot my runesetup after confirming the setup.
• If a player is caught cheating it result in a automatic loss of the complete match.
• More two or three judges will always look at submitted complications and decide on further penalties that may result in:
• Disqualification of team/player from tournament/league
• Disqualification of player in team from tournament/league

You can use the D3CL PvP rules in any competitions not organized by D3CL but you have to leave notification: "D3CL PvP Rules www.d3cl.com" with clickable link.