What does the service judge watch for?

Question

Accepted Answer

The service judge sits on a low chair by the net post, opposite the umpire, and calls service faults by the server (Law 17.3, covering Laws 9.1.2 to 9.1.8). On a fault, call "Fault" loudly and give the approved hand signal; the umpire then acknowledges it and explains the fault.

What to watch, under Law 9.1:

Law	The server must...
9.1.2	not delay starting the forward swing once the backswing is complete
9.1.3 / 9.1.4	stand inside the service court without touching its lines, with part of both feet on the floor and stationary until the shuttle is hit
9.1.5	release the shuttle without adding spin and hit the base of the shuttle first
9.1.6	have the whole shuttle below 1.15 m from the floor at contact
9.1.7	keep the racket moving forward from the start of the serve until it's delivered
9.1.8	not miss the shuttle

Where the BWF alternative service law is used, the height test is instead: whole shuttle below the server's waist (level with the lowest rib), with the racket shaft and head pointing downwards at contact.

Other duties (BWF Instructions to Technical Officials): handle shuttle changes as the umpire instructs and keep enough shuttles ready; extra tasks the umpire assigns, such as checking the posts are on the doubles sidelines, the service height device is in place and level, the net height, or calling the nearest sideline when there's no line judge; check Instant Review challenges are administered correctly; and alert the umpire straight away to any potential mistake, standing up and crossing the court if necessary.