How does one become an Arbiter? What is the gig there?

"Maybe you already noticed them: Forum users with a green name and a green icon. These people are our Emissaries. The emissaries are a small group of volunteers who support Riot with everything that is related to the community. Like the word “Emissary” suggests, they are the link between Riot and the players and represent their local community.

The emissaries help moderate the forums, forward important ideas, questions, problems and feedback, organize projects and events and are the persons to talk to for everyone. With their knowledge and experience they support and promote constructive discussions and are able to help with a lot of problems.

The emissaries are pillars of the community who stand out with their knowledge, helpfulness, constructive posts, ideas, enthusiasm and, most important, their joy in helping other players.

So what can the emissaries help you with?

• If you have a problem or a question about  anything connected to the game (player behavior, matchmaking, fan art etc.), the emissaries can often help, answer the question or get the answer from Riot
• If you need guidance or advice for organizing an event, a community or a project, the emissaries are able to help
• If you have an idea, the emissaries can give you valuable feedback
• If a discussion on the boards escalates and becomes a flame war, the emissaries can step in
• If you have a problem with (your own or other peoples) behavior, the emissaries can help you to deal with the situation

How do the emissaries help you?

• They are active on the boards. If you write a thread on the boards, it’s quite likely an emissary will see it sooner or later, especially if you managed to keep it constructive ;)
• Together with the other volunteers, emissaries can be contacted via their own new platform leaguecom.net
• If you want to contact individual emissaries, use the usual methods like social media or adding them to your friendlist in the client
• Last but not least, emissaries help invisibly. Moderation or discussions with Rioters are just two examples for this kind of “behind the scenes”-help

What are emissaries NOT?

• Emissaries are focused on the human side of League of Legends. If you have a technical problem (FPS problems, unstable connection, bugs etc.), you should contact the wrenchmen instead.
• Emissaries are NOT  Rioters. They don’t get paid and everything they do is voluntarily, they don’t HAVE to do or say anything. Although emissaries normally have quite a deep insight in a variety of topics, their words should not be mistaken for official statements.
• Emissaries are not told to be “pro Riot”. Providing negative feedback for Riot is one of the main tasks of all volunteers.
• Emissaries won’t be able to tell you release dates of skins or any other “secret stuff”…because they simply don’t know it.
• Emissaries are no pro players. Although most emissaries have a lot of gaming experience, we didn’t select them because of their ELO.

Final note:

Always keep in mind that emissaries as well as wrenchmen invest their free time outside of school, work or university to help people without getting anything for it…except the joy of helping others. So please treat them with respect and don’t be unthankful if they are not able to help you immediately.

#OK

That's the full description for "Emisssaries", but it's pretty much the same as Arbiters. The Arbiter Program announcement can be found here though; http://boards.na.leagueoflegends.com/en/c/player-behavior-moderation/opVBd7rZ-introducing-the-arbiters