Overcalling Opponents Opening bid of 1C! or 1C|1D 

♣  ♥  ♠  ♦

Raison d'etre

BETA now opens 1♣ more frequently than any other bid showing: 2+ cards  & 12-18 HCP and fairly balanced hands.
More distributional hands follow other paths. There is a growing tendency for other Systems to also increase their frequency of opening 1♣|♦  with a definition of 'better minor' or simply just 1♣ -showing 2 or 3+ cards and opening values.... As a consequence of this it behoves us to examine avenues of taking advantage of this situation. This document is an initial attempt. On one hand we aim to make bids to disturb their sequences and consume their bidding space with moderate values and on the other hand have bids that can show our strength and distribution when we have it. A balanced approach. We commend the following specifications, applicable to BETA ONLY, now formally adopted.  Note  precision 1♦ openings are also included  in this approach too as well as 'better' minor.

NOTE: Exception is a 1♣! alerted to be Strong - e.g Precision or other strong Club systems showing at least 16+HCP. Beta's defence in this case remains:  TRAP.

Beta's motivation for the following 3-pronged approach is based on making best use of all bidding space the opponents have granted us!  Of course if  none of  'ABC' below are appropriate then bid PASS!

A) DOUBLE. Adopts their 1♣ opening bid as our own :- we can state we are in 1st and I have a BETA 1♣ opening position and with a simple DOUBLE. This states "we would have opened 1♣ ourself!! This  adopted  1♣! shows our  usual 12-18HCP 1♣ opening bid. Partner responds with the usual BETA sequences following partner's now assumed 1♣ opening!
 A bis) Opponents open 1♦. Double now operates in a similar way: announces that we would have opened 1♣ showing 12-18.
In either case partner is expected to respond as if 1C 12+ had been opened.
E.g. 1♦(opp)-*-1♠(opp)-* Shows Hearts!

 B) 'Ignoring' ....the opponents 1♣|♦ opening.
 
Partner in 2nd position simply makes an overcall 1 of ♦|♥|♠ over opponents 1♣ opening showing: 10+ HCP and a 5 card suit ♥|♠|♦ respectively (note transfer o'calls!). Also similarly overcalls ♥|♠ over 1♦ showing the OTHER major opening by opponent.
Note: These are 1-level opening bids - these are not O'calls! They show 10+ HCP & a 5+ card suit. BETA 1♦(5+♥'s); 1H(5+♠'s ); 1♠(5+♦'s). Over 1♦ overcalling 1♥ or 1♠ announces normal 5+ card BETA openings.
There is one difference to when  1♣-1♠ BETA shows 10+ denying 5+ card major  showing 5+♦'s.
Partner continues as if partner's 'o'call' had actually OPENED the bidding!   BUT all must recognise and remember that your LHO's has shown opening values - and nothing else as yet!

C) BETA Attacks! with the best of BETA by making alertable overcalls of 1N or higher over opponents 1♣ or 1♦ can be 2+ or 3+ card minor short openings.

Over 1C: 1D shows 5+Hearts, 1H: 5+Spades & 1S: 5+Diamonds
Over 1D: 1H & 1S are natural 5+ cards

The above bids may not be used if any of the following bids namely: 1N, 2C, 2D, 2H, 2S, 2N, 3C or 3D and any pre-empts 3H and above are appropriate:

These following bids of 1NT or above are all aimed at either disrupting opponents bidding, showing specific strong hands or presenting 2-suited hands or pre-emptive bids: all of which can effectively disrupt the opponents normal bidding - primarily by robbing them of their bidding space: thereby disrupting their bidding or showing our strength or strong distributional strength. These BETA 'coded' alertable bids as specified in BETA that are usually opening bids  e.g 2♦, 2Ma or 3mi but now available as o'calls but carrying the same message. Also bids such as 2♣, 1NT or 2NT which are usually overcalls and above follow with distributional meanings as given below:-

1NT! Our multi 1NT o'call. There are several meanings but the most frequent of which is: Showing Both minors at least 5+-5. Partner required to bid 2♣ if his RH opponent passes. Rebids show a variety of hands:  3♣ both minors weak 6|7 LTCor 2♥ strong <=5 LTC. Both showing 5+-5 in the minors. a 2♦ rebid shows a balanced 2♣ or * if intervention shows opening of 23+ HCP. Rebid of 3♦|♥|♠ shows a 2♣ opening <=3 1/2 LTC with a quality ♦|♥|♠ 5+ card suit & NO 2nd suit. Following 2♣ provide your Honour strength in up to 4 steps 2♣ style, Following 3♦|♥|♠ Show your trump support in 4 steps as defined in regular 2♣ sequences.

2♣! Both majors 10+ 4-4. Denies both Majors 5+-5+ use 3♦ below. 
Also stronger 5+ Ma-4any hands <=5LTC use 2Ma below.

2♦! Our versatile multi 2♦ - a 3-way bid: a) Weak Major 2 b) 19-20 Balanced c) 5-5 or better in either Clubs & Hearts OR Diamonds & Spades

2Ma! Not at all weak 2's! Shows <=5 LTC with 5+ Card Major and a 2nd suit of 4 cards. Partner may PASS, Raise OR inquire  with 2N. May also be used to show  a  quality 6+ card suit and  <=5LTC

2NT! Shows Spades & Clubs at least 5-5 &  <=7LTC

3♣: shows both red suits at least 5-5 <=7LTC 

3♦: shows both Majors at least 5-5 <=7LTC.

3♥ and all higher suit bids are all pre-emptive openings in BETA usually (6)7+ cards.