Although the specific facts of the dispute between junior doctors and Jeremy Hunt are pretty unique and will not be of direct relevance to many employers, it does serve as a very timely reminder of an often overlooked legal principle.

Put bluntly, it is not easy to change contractual terms unless both parties agree.

During employment the parties will often want to make changes to the terms which were originally agreed at the outset. Some of these changes may not be controversial. Needless to say, an employee is unlikely to object to changes which are beneficial such as a pay rise or the introduction of new benefits. Of course, changes which are onerous or at least are 'seen to be' onerous will be harder to effect without running the risk or a breach of contract and/or constructive unfair dismissal claim. One solution may well be trying to buy consent by offering a range of other benefits as a package to offset the less popular changes.

However, an area I often see employers trip up in is where they mistakenly believe they have free reign to make changes as the contract itself (or the specific clause in question) which they want to change purports to permit them to do so unilaterally. For example, it is common to see clauses which state a certain shift pattern will be worked but the employer has complete discretion to vary this. The point that is frequently overlooked when relying on these clauses is that they must always be enforced 'reasonably'. As a result, a significant change (or one which disproportionately impacts on the employee could still be unlawful. In addition, the way the employer imposes the change itself could also be seen as unreasonable.

If in any doubt it is therefore sensible to err on the side of caution and get some specific guidance. Not least as it is clear from the current dispute employees can feel extremely aggrieved when they feel the goal posts are changing unfairly.