The trial bid investigates Game possibilities. It chiefly considers the majors and follows a limit raise to the two level.

In a natural sequence the bidding might go as follows:

North	South
1♥	2♥
3♥

Instead North can use the “Trial Bid” to find out more:

North	South
1♥	2♥
3♣

So instead of the natural 3♥ rebid North replaces it with 3♣ as a rebid to ask  partner for assistance in that side suit. The trial bid shows North is a little too strong to pass, but too weak to push to Game without some support in clubs. Regardless of where his values lie South responds as follows:

1. With minimum value for a raise (6 points) bid 3♥
2. With maximum value for a raise (9 points) bid 4♥
3. If doubtful, South will choose between a bid of 3♥ or 4♥ based on his actual ♣ holding.
4. Pass the buck by showing side strength at the same level, eg, 3♦

In another example the 3♥ is the trial bid:

North	South
1♠	2♠
3♥

South will reply 3♠ for no control, or 4♠ to show controls in ♥s.

In the next example the 2♥ on rebid is the trial bid. Following the minor sequence, 1♦ – 2♦ it indicates a stop in ♥s. North is seeking a Game contract in NT, and is therefore asking partner for help, not in the trial suit bid, but in any of the other suits. Here, South obliges by showing ♠s.

North	South
1♦	2♦
2♥	2♠

In the final example South cannot help, and bids 3♦ . It is a repeat of the agreed suit as a negative response. Here the trial bid has helped the partnership avoid a dangerous contract in No trumps

North	South
1♦	2♦
2♥	3♦

Examples

North as opener
♠ A Q J 9 6
♥ A J
♦ 9 8 5
♣ K Q 8

North	South
1♠	2♠
3♦	?

North’s trial bid of 3♦ shows he is weak in his ♦ side-suit and needs help if they are to reach a Game contract.

South replies:

1) On minimum for the raise (i.e 6 points), he will sign off at the three level, bidding 3♠.
2) On maximum (i.e 9 points) he goes to Game, bidding 4♠.
3) If in doubt, he checks his trial suit (♦s). He would go to Game with a singleton or doubleton in ♦s, or if he held an honour (A,K or Q).

In this next hand North’s 2♠ is the cheapest trial bid he can make; although he is looking for the ♦A. However, an ♠A might give him Game strength with second round roughing values already held in his ♥ suit.

North as opener
♠ K J 9 3
♥ A Q J 10 7
♦ 8
♣ A J 8

North	South
1♥	2♦
2♠	?

Finally, trial bids in the minors are used to explore a 3NT possibility when a minor Game seems unlikely.

North as opener
♠ 7
♥ A 9 7
♦ K Q J 9 7 5
♣ A 6 3

Again 2♠ is the cheapest suit for a trial bid, though it is not North’s only weakness. However, if South has a partial stop in ♠s, North can see 3NT. Being in the minors, South will bid any suit in which he has a stop, not necessarily the one North has called.

1) With a stop in spades South will bid 3♠. North will go to 3NT.
2) With no stop in spades South will bid 3♣ to show a ♣ stop. In response North will stop below Game at 3♦.

North	South
1♦	2♦
2♠	?

Confusion between cue bids and trial bids

You may at first be confused between cue bids and trial bids. In most cases they both follow a raise of opener’s suit: a trial bid follows a single raise; a cue bid follows a double raise:

North	South	Notes
1♠	2♠	On rebid North may trial bid
1♠	3♠	On rebid North may cue bid
1♥	3♣	By partnership agreement, North may cue bid next

Cue bids are distinguished from trial bids in that they operate when the opening bid has been raised to the three level, or when the trump suit has been agreed upon by inference and a slam is looking promising. The cue bid shows first round control in the lowest ranking suit held (an Ace or a void), and asks partner to cue-bid his lowest-ranked control in reply.

The trial bid does not deal with controls. It follows a limit raise to two of a suit, and investigates a Game possibility, not a slam. And it usually concerns the major suits.

Definitions

Control. The ability to win the first or second trick in a suit. The context is usually used in slam bidding. First round control is an Ace or a void; second round control is a King or a singleton [See Chapter Fifteen]

Small slam. A small slam is a contract to make twelve of the thirteen tricks. It is also known as a “Little Slam”.

Trial bid. A trial bid is signalled by a limit raise to the two level. It is used to investigate Game possibilities, primarily in the major suits.

Cardinal rules

Rule No 14 – Opening one of a suit promises a rebid, even if his partner does not bid.
Rule No 15 – A no trump response from partner indicates no biddable suit.
Rule No 16 – After any no trump limit bid opener is no longer obliged to rebid.

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By Nigel Benetton – based on the UK Acol Bridge Bidding System
Last updated: Thursday, 29 April 2021