The issue in this case related to a collective agreement struck between the claimant employer and the respondent trade union. The agreement included a provision that a productivity bonus for employees would be consolidated into their basic pay.  The issue is that one of the Union’s members (Anderson) brought a claim for unlawful deduction from wages citing that they were entitled to an enhanced shift allowance.  As it had not been enhanced they brought the claim and the Tribunal upheld it.  The remedy decision in that case has not been made yet.

The claimant employer sought to bring proceedings to rectify the collective agreement on the basis of mistake.   They stated that the provision allowing for an enhanced shift allowance was not the intention of the parties. At first instance, the respondent’s argument was rejected that the claimant was estopped from pursuing rectification on the basis that it was not raised within the individual proceedings brought by Anderson.   The Union appealed this to the Court of Appeal.

The first issue was whether rectification, as a matter of contract law, was available in relation to the collective agreement.  The Court of Appeal held that rectification could be available against the employees whose legally binding contracts would be affected.  However, it could not be available in relation to the collective agreement as it was not a legally binding contract in of itself.  It would only be changed by the parties expressly agreeing to do so.   Therefore, the proceedings would have to be brought against the individual members and not the Union.  The Court of Appeal also outlined that such an argument could not be raised against members who had already brought claims as that would be res judicata (already decided upon in earlier proceedings).   However, it is the case that it could be raised as a defence in any future proceedings.

Practical Lessons

This case demonstrates the full position of contract law ‘devices’ when it comes to collective agreements.  The whole basis of contract law is to regulate legally binding agreements.  However, as the collective agreement does not satisfy that criterion it follows that such equitable remedies, such as rectification, as used in contract law could not be applied.  This puts the claimant in the uneasy position of having to do it against the individual members who do have a legally binding agreement through their contract of employment. 
https://www.casemine.com/judgement/uk/60bdbc3d2c94e055d83d3d64