Per the site rules:
Brigading: Calling for group downvoting (or group upvoting) of an article is prohibited. Being part of a vote brigade may lead to a ban.
Note: Not every call to check out an article by someone who dislikes it is brigading. Context and intent will determine whether or not an incident is considered brigading.
Due to the inherent difficulties in ascertaining whether someone is privately calling for a brigade, context and circumstances are used in determining whether a brigade has occurred, and staff found that it was unlikely the voting behavior was organic based off the user's previous voting history on EN.
Organized voting behaviour to artificially increase or decrease an article’s score is considered brigading and is grounds for disciplinary actions, up to and including a permaban. Voting on the translation of an article on a different branch, and then coming to EN to mirror that vote en-masse is considered brigading on EN and may result in disciplinary action. The Disciplinary Team would like to make it clear that this position does not change regardless of the site, branch, or users in question, or whether the vote manipulation is in the positive or negative direction. Staff reserves the right to take disciplinary action against users suspected of participating in a brigade with the intent of artificially altering an article's rating.