Scope
The BWF international baseline used here
This page applies the Badminton World Federation Laws of Badminton, Section 4.1, updated 1 July 2026, and the BWF Instructions to Technical Officials (ITTO), Section 4.1.1, effective 1 July 2026. The central provisions are Laws 9, 14 and 17 and ITTO Sections 2 and 5–8.
The ITTO applies generally to Para badminton, but a specific Para badminton instruction supersedes it where adopted. The size of the officiating crew, availability of IRS and any alternative service law depend on the appointed competition's regulations. Club, school and domestic events should not be assumed to provide the same officials or review system as a BWF-sanctioned tournament.
Officials at a glance
Who is responsible for what?
- Referee: has overall authority for the tournament or championship. The Referee appoints the Umpire for a match and remains the final authority on unresolved questions about interpreting the Laws.
- Umpire: is in charge of the match, court, and immediate surroundings. The Umpire enforces the Laws, calls faults and lets, announces the score, handles appeals, manages the other on-court officials, and reports to the Referee.
- Service judge: decides whether the server complies with BWF Laws 9.1.2 through 9.1.8. The service judge calls a service fault and uses the approved signal identifying the broken service requirement.
- Line judge: decides in or out for the line or lines assigned to that position. The line judge does not decide net faults, player contact, service order, or the score.
This division comes from BWF Law 17 and ITTO Section 2. The Referee normally appoints the on-court officials; the Umpire may appoint or remove a line judge or service judge after consulting the Referee. A court can operate with fewer officials, but the Umpire must arrange for every unfilled duty to be performed.
Referee versus Umpire
The Referee does not normally call each rally
In BWF terminology, the Referee runs the event while the Umpire sits in the chair and controls an individual match. The Umpire decides ordinary match questions without asking the Referee to confirm every ruling.
The Referee becomes involved when called to court, when an unresolved appeal concerns interpretation of the Laws, when a tournament-level decision is required, or when the Umpire reports serious misconduct. An appeal about what physically happened is not converted into a question of law merely because a player disagrees with the on-court official.
Umpire control
The Umpire combines decisions, announcements, and match management
BWF Law 17.6 requires the Umpire to enforce the Laws, call a fault or let when appropriate, decide timely appeals, keep players and spectators informed, arrange unfilled officiating duties, record and report Law 16 incidents, and refer unresolved questions of law to the Referee.
The Umpire also confirms the score and which side serves. The score is always announced with the serving side's score first. “Service over” means that the right to serve has changed; it is not a separate penalty or an extra point.
Umpire signals
Most Umpire rulings are spoken, not mimed
The BWF ITTO effective 1 July 2026 relies on standard vocabulary such as “Play,” “Fault,” “Let,” “Service over,” the score, and specific correction or review announcements. There is no general catalogue of Umpire gestures that substitutes for these spoken calls.
- Right hand raised above the head: the Umpire is calling the Referee to the court.
- Left hand raised above the head: in the Instant Review System procedure, the Umpire is requesting or administering review of a line call.
- Pointing right or left: the Umpire identifies the players or sides during the match introduction where required.
- Yellow, red, or black card held above the head in the right hand: the Umpire is communicating a misconduct warning, misconduct fault, or Referee-ordered disqualification. The card procedure is explained in the badminton misconduct and penalty-card guide.
A player should follow the Umpire's announcement and the resulting score rather than infer a ruling from a single movement viewed out of context.
Fault and let calls
Silence does not always mean that no decision was made
The Umpire normally announces “Fault” when a fault occurs. The 2026 BWF ITTO allows the announcement to be omitted for certain obvious faults and when a line judge's out call and signal already communicate the decision. The Umpire may still explain the ruling when players or spectators need clarification.
“Let” stops and replays play since the last service: the previous server serves again and the intervening rally does not count. It is used only when a BWF Law creates a let, including the narrow case where an assigned line judge is unsighted and neither the Umpire nor the available review system can decide the landing.
Service judge
A service judge watches the server, not every service dispute
Under BWF Law 17.3, the service judge calls faults committed by the server under Laws 9.1.2 through 9.1.8. These include undue delay after the backswing is complete; standing on a service-court line or moving a foot before delivery; not releasing the shuttle before striking its base first, or adding spin on release; contacting any part of the shuttle at or above 1.15 metres; failing to continue the racket's forward movement; and missing the shuttle while attempting to serve.
The service judge calls “Fault” loudly and uses the official BWF hand signal for the specific violation. The Umpire then confirms that the fault is against the server and uses the standard vocabulary to identify the reason. The diagrams in ITTO Section 7 are the controlling visual reference; an informal gesture learned at a club does not replace them.
The Umpire still watches the receiver and may also call a service fault. The service judge may additionally manage shuttle changes and perform other tasks assigned by the Umpire, such as checking the net or an uncovered sideline.
Competition variation: ITTO 7.4.1 identifies the BWF Section 4.1.4 alternative to the 1.15-metre test. Where the competition adopts it, the whole shuttle must instead be below the server's waist at contact and the racket shaft and head must point downward. Check the event regulations before deciding which service-height signal applies.
Line judge — out
“Out” is both a voice call and a two-arm signal
When the shuttle lands outside an assigned boundary, BWF ITTO 8.3 effective 1 July 2026 instructs the line judge to call “Out” promptly and clearly, extend both arms horizontally to the sides, and look toward the Umpire. The signal is required even when the shuttle is a long way outside the line.
The landing must be judged against the boundary active for that rally. A shuttle touching the applicable line is in under BWF Law 1.3. Singles, doubles, and service can use different boundaries; the in-or-out and line-call guide explains those choices in detail.
Line judge — in
An in signal is deliberately silent
For an in landing, the line judge says nothing, points to the line with the right hand, and looks at the Umpire. That silence is the prescribed BWF procedure when paired with the pointing signal; it is not indecision.
The line judge must wait until the shuttle touches the floor or something outside the court before calling. A bounce or slide after impact does not change the landing point.
Line judge — unsighted
Both hands over the eyes means no view
If the line judge could not see the landing, BWF ITTO 8.5 requires both hands to cover the eyes immediately. This is an unsighted signal, not an in call and not a request to guess.
The Umpire then decides if able. If the Umpire is also unable to decide and no Instant Review System supplies a decision, BWF Laws 14.2.6 and 17.6.6 require a let. Where review is operating, the Umpire announces that the call was not seen, raises the left hand, and asks the system for a decision.
Earlier faults
A line judge reports the landing even if another fault appears obvious
BWF ITTO 8.7 effective 1 July 2026 instructs line judges to make their assigned call without waiting for the Umpire's ruling on another fault. For example, a line judge still reports the landing even if the shuttle appeared to touch a player, clothing, or racket first.
This preserves each official's evidence. The Umpire then decides the full sequence and applies the earliest decisive event under the Laws; the line judge does not abandon an assigned factual observation to decide a different kind of fault.
Overruling
A close call is not enough reason to overrule a line judge
BWF Law 17.5.1 sets a high threshold: the Umpire overrules when it is beyond reasonable doubt that the line judge clearly made the wrong call. The Umpire then immediately announces “Correction, IN” or “Correction, OUT.” The replacement call becomes the match decision.
This power is an exception to the usual rule that the official assigned to a factual question makes the final decision. It is not a licence for the Umpire to reconsider every close landing or to prefer a player's view.
Instant review
Video review replaces the original line decision where available
When the BWF Instant Review System is operating, a player must say “Challenge” and/or clearly raise a hand immediately after observing the line decision. The Umpire verifies that the player has a valid challenge, announces it, and raises the left hand while the system reviews the call.
An IN or OUT system result controls the landing. If the system returns “No Decision,” an existing seen call remains in force; an original unsighted call becomes a let. Under BWF IRS Section 4.1.8, a player or pair may keep challenging until two challenges have failed in that game. A successful challenge, an Umpire-requested review and a “No Decision” do not use up a challenge.
If text and graphics conflict or the IRS result is obviously wrong, the Umpire does not improvise a replacement decision: ITTO 5.8.10 requires the Umpire to call the Referee before the next rally, and the Referee directs how play resumes.
Appeals
Facts and interpretations follow different routes
Under BWF Law 17.6.2 effective 1 July 2026, a player must raise a disputed point before the next service is delivered. The Umpire decides the appeal. If the player remains dissatisfied, only an unresolved question about interpreting the Laws is referred to the Referee.
- Fact: “The shuttle landed outside.” The assigned line-call process decides this, subject to the stated overrule and review exceptions.
- Interpretation: “The wrong rear boundary was used for this doubles serve.” This concerns which Law applies and may be referred to the Referee if unresolved.
- At match end: an appeal must be made before the appealing side leaves the court.
A player may ask for clarification, but cannot require the Umpire to consult spectators, coaches, or an unofficial recording. BWF ITTO 6.9 specifically tells Umpires not to ask or be influenced by spectators.
Reduced crews
Not every match has the full international officiating team
BWF Law 17 allows the Umpire to arrange for unfilled duties to be performed. With no appointed line judge, the Umpire makes the line decision. The 2026 BWF ITTO also permits the service judge to cover a nearby sideline after players are informed.
A recreational or school match with no appointed Umpire does not suddenly acquire the full BWF chair-umpire signal procedure. The organiser's rules should identify who calls lines and resolves disputes. Any local procedure allocates responsibility; it should not be presented as a universal BWF officiating rule.
Decision path
How an on-court ruling is resolved
- Identify the event. Is it a service-delivery fault, a shuttle landing, another rally fault, misconduct, the score, or a question about what a Law means?
- Identify the responsible official. Use the service judge for Laws 9.1.2–9.1.8, the assigned line judge for that boundary, and the Umpire for the match and all unfilled duties.
- Check whether the official saw it. A seen factual call normally stands. If a line judge is unsighted, the Umpire decides if able and otherwise asks IRS where it operates.
- Apply the narrow replacement route. The Umpire may correct a clearly wrong line call beyond reasonable doubt; a valid IRS result replaces the original call.
- Choose the outcome. A fault ends the rally and the opposing side wins the point; a let cancels play since the last service and the previous server serves again; a corrected or reviewed line call is scored according to the replacement decision.
- Raise any appeal in time. Disputes must be raised before the next service. Only an unresolved question about interpreting the Laws goes to the Referee.
Worked case 1
The line judge is screened at the baseline
Situation: the shuttle lands close to Blue's baseline, but a player blocks the line judge's view. The line judge immediately covers both eyes. The Umpire had a clear view.
BWF 1 July 2026 ruling: the Umpire makes the IN or OUT decision under Law 17.6.6 and ITTO 5.8.3. There is no let merely because the assigned line judge was unsighted; the decisive fact is that the Umpire can perform the missing duty.
Worked case 2
A player challenges an Umpire overrule
Situation: the line judge calls OUT, the Umpire announces “Correction, IN,” and the player immediately challenges on a court using IRS.
BWF 1 July 2026 ruling: the challenge is permitted because BWF IRS Section 1 covers a line judge's call and an Umpire call or overrule. The IRS result replaces the overrule. If it returns “No Decision,” the Umpire's existing IN decision stands and the player loses no challenge.
Worked case 3
A service is struck exactly at the height limit
Situation: under the standard BWF service law, part of the shuttle is level with 1.15 metres when the racket makes contact.
BWF 1 July 2026 ruling: service fault. Law 9.1.6 requires the whole shuttle to be below 1.15 metres at contact. The receiver's side wins the rally and point. Under an event using the alternative service law, this measurement is not the test; waist height and the downward direction of the racket shaft and head control instead.
Worked case 4
A player waits until after the next serve to object
Situation: a player believes the wrong service court was used but says nothing until the next service has been delivered.
BWF 1 July 2026 ruling: the appeal is too late under Law 17.6.2. If raised in time, the Umpire would decide it; only an unresolved issue about interpreting the Law could then be referred to the Referee.
Common mistakes
Misunderstandings to avoid
- “The Referee sits in the chair.” In BWF terminology, that match official is the Umpire; the Referee controls the tournament.
- “A silent line judge called nothing.” An in landing is communicated silently by pointing at the line.
- “Both hands over the eyes means in.” It means the line judge was unsighted.
- “The Umpire can freely change a close line call.” BWF Law 17.5.1 requires a clearly wrong call beyond reasonable doubt.
- “Any disagreement is a let.” A seen factual call remains a decision; the unsighted let applies only when the authorised decision-makers cannot decide.
- “A service judge decides whether the serve landed in.” The service judge judges the server's delivery; the assigned line judge or Umpire decides the landing.
- “Every Umpire decision has a hand signal.” BWF procedure is primarily verbal, with particular gestures for defined situations.
Official references
Governing-body sources and effective version
Checked on 13 August 2026 against the BWF Laws and ITTO publications effective 1 July 2026 and IRS Version 2.0. The linked 2026 Laws and ITTO are Badminton Denmark's current Danish publications of the BWF documents, with their effective dates confirmed by its Technical Officials Handbook index. Competition regulations may alter crew size, provide IRS or adopt an alternative service law; those event-specific choices are not universalised here.