The two sides in an employment tribunal case are normally required to disclose to each other all the documents they have that are relevant to the dispute. An important exception to this rule is ‘privileged’ documents: that is, communications with their lawyers for the purposes of legal advice (‘legal professional privilege’) and communications or documents created for the purposes of pursuing or defending the claim (‘litigation privilege’). (For a fuller explanation, see paragraphs 4.29-4.36 of the book.)
Legal professional privilege is often particularly important. Your employers may have gone to their lawyers when you first made your request for reasonable adjustments – for example – and asked ‘Do we have to do this? Can’t we just sack her if she can’t do the job any more?’ Their lawyers may have written them a long sorrowful letter of which the gist is ‘Unfortunately not: there’s this really annoying bit of legislation called the Disability Discrimination Act. You will have to go through the motions at least.’
Obviously if the Tribunal was shown this correspondence, it could help you win your case, so you’d like to get your hands on it. But normally you’re not entitled to, because it is privileged.
Employers can be careless, though, about accidentally waiving privilege. If they mention the legal advice that they have received in their witness statement, they may have waived their legal professional privilege and given you the chance to demand to see the advice. If, for example, they say something like “We took legal advice on our duties under the DDA, and we followed it to the letter,” you can ask the tribunal to order them to disclose that advice to you.
You may want to rely on either or both of the following quotes:
Paragon Finance v Freshfields  1 WLR 1183, 1188 C-D (Lord Bingham):
‘A client expressly waives his legal professional privilege when he elects to disclose communications which the privilege would entitle him not to disclose. Where the disclosure is partial, issues may arise on the scope of the waiver. Practical difficulties occur in determining such issues…. But the law is clear. While there is no rule that a party who waives privilege in relation to one communication is taken to waive privilege in relation to all, a party may not waive privilege in such a partial and selective manner that unfairness or misunderstanding may result.’
Nea Karteria Maritime Co Ltd v Atlantic & Great Lakes Steamship Corporation, quoted by Waller LJ in Dunlop Slazenger International Ltd v Joe Bloggs Sports Ltd  EWCA Civ 901 at paragraph 11:
‘Where a person is deploying in court material which would otherwise be privileged, the opposite party and the court must have the opportunity of satisfying themselves that what the party has chosen to relase from privilege represents the whole of the material relevant to the issue in question. To allow an individual item to be plucked out of context would be to risk injustice.’
Be prepared for a tussle if you make a request of this nature. Not all employment tribunal judges will have the rules about waiver of privilege at their fingertips, and employers and their lawyers are likely to oppose the application vigorously. So go armed with full copies of the authorities, and explain carefully why you say privilege has been waived in your case. You might also want to take copies from Phipson on Evidence (16 ed. Sweet & Maxwell 2005) paragraphs 26-15 and 26-16. (You are likely to need to get access to a law library for this. Phipson is a difficult, dense book written for practising lawyers. Even if you find it hard to understand yourself – don’t feel stupid if you do, as it is the kind of material that plenty of trained lawyers find daunting – you are entitled to assume that the employment judge in your case will be able to cope with it.)