Four players per table form two sides, North-South and East-West (Law 4); In pair or team events contestants enter as pairs or teams and keep the same partnership throughout a session; in individual events partnerships change during the session (Law 4); The Director assigns an initial position to...
Source: Law 4, Law 5, Law 6 — American Contract Bridge League — Laws of Duplicate Bridge
Why people argue about this
People often argue about how partnerships are formed in Duplicate Bridge because they misunderstand that while pairs enter as teams for a session, their initial positions (North-South or East-West) are assigned by the Director based on the order of play rather than their partnership status, leading to confusion about who plays with whom.
