Many employment cases involve disputes about calculations, often relating to sums of money, but also other issues, such as hours worked or weeks employed.

Normally the dispute is about what calculation needs to be made. For example, the claimant will say that he is entitled to 3% commission on his sales, while the respondent claims he is entitled to 2.4%.

Surprisingly often, however, the dispute comes down to a difference in the result of the calculation. For example, the parties agree that 3% commission is owed and that it is on the invoices to be found from page 70 to 77 in the bundle, but cannot agree a final figure. The claimant claims he is owed £3,544, while the respondent insists it is £2,898. The difference is purely arithmetical and it seems obvious that one party must have got its sums wrong.

In an ideal world, such errors would not occur and, if they did, would soon be resolved amicably. In this, less than ideal world, the question arises, should an advocate cross-examine a witness on his maths?

The authors believe not. While the maths may be a question of fact, it is not one that is likely to be illuminated by careful cross-examination. Instead, the sums should be set out in the submissions and the tribunal can, if necessary, do its own arithmetic to check them.

It should be noted, however that this is not necessary the general view and that the authors are aware of at least one tribunal who took the position that a witness should be taken through his calculations. The most sensible approach is to seek guidance from the tribunal, by saying something like “Sir, there is an issue regarding the calculation of this figures. It comes down to a question of arithmetic. Unless you think it would be helpful for me to take the witness through the sums in detail, I think it can be dealt with in submissions.”

The final point to note is that, in an appropriate case, the tribunal’s own arithmetic can be challenged by way of appeal, see Mears v Lloyd Green & Co. for an example. In most cases, however, a tribunal’s mistaken calculation is more appropriately dealt with by applying for a certification of correction or a review.

One of the important techniques in cross-examination is leading up to an important point with the right preliminary questions. The key is to place the witness in a position from which it is difficult to give the ‘wrong’ answer.

For example:

Sir Humphrey: Mr. Woolley, are you worried about the number of young people without jobs?
Bernard : Yes
Sir Humphrey: Are you worried about the rise in crime among teenagers?
Bernard : Yes
Sir Humphrey: Do you think there is a lack of discipline in our Comprehensive schools?
Bernard : Yes
Sir Humphrey: Do you think young people welcome some authority and leadership in their lives?
Bernard : Yes
Sir Humphrey: Do you think they respond to a challenge?
Bernard : Yes
Sir Humphrey: Would you be in favour of reintroducing National Service?
Bernard : Oh…well, I suppose I might be.
Sir Humphrey: Yes or no?
Bernard : Yes

Or if you want the opposite answer:

Sir Humphrey: Mr. , are you worried about the danger of war?
Bernard : Yes
Sir Humphrey: Are you worried about the growth of armaments?
Bernard : Yes
Sir Humphrey: Do you think there is a danger in giving young people guns and teaching them how to kill?
Bernard : Yes
Sir Humphrey: Do you think it is wrong to force people to take up arms against their will?
Bernard : Yes
Sir Humphrey: Would you oppose the reintroduction of National Service?
Bernard : Yes

Even if the witness is willing to stick to their guns, if they have been pinned down properly the damage will be done. A witness who has accepted that they are responsible for London sales; that their bonus is based on those sales; that Stuff Ltd is a very important client and that Ms Jones was responsible for their buying decision will only appear foolish if they try to deny that they have been willing to go to great lengths not to offend Ms Jones.