So one judge defines it to be so, and it is for ever more? Another judge is not allowed to say differently?
What?
If you are making a serious point, then I do suggest that you look elsewhere for your answers, and hope that you enjoy the discovery of how law evolves.
Briefly, in the UK, our Common Law system does evolve, and even the most ancient of our inheritance of Judgements receive 'adjustments' almost every week. The development of IT and the media, for examples, continue to challenge the received cannon of Judgements. Ancient principles of Nuisance, Negligence, Trespass etc. are continually updated by Judgments in Courts today. But I'm sure you must know this.
One of the great benefits of the Common Law system (in which a prior Judgement determines a subsequent application of the same statute or tort) is one of consistency. i.e. someone accused of Theft in Shrewsbury is dealt with by applying the Law in the same way as someone accused of Theft in Whitby. By referring to the explanation of how to apply the evidence to the Law in the same way across the country, then all of us, citizens, business people, opportunists, law enforcers and others, can all expect the same outcome from a challenge in Law.
This is the basis of how applying rules and how updating the rules actually works in Law.
The benefit of having Law clarified by the Courts rather than by lawmakers has become so popularly accepted that the Guidance notes published with new legislation often leaves some terms undefined, explicity stating that it will be for the Courts to decide how to interpret the text - Courts who are facing real-world facts and circumstances, so that others in future can benefit from the decision of another Court dealing with similar circumstances, rather than the suppositions of a government department's lawmakers.
Of course a Judge is allowed to determine a matter in opposition to a prior judgement! And they do. But they will be giving a good and reasoned argument for doing so and will be exposing the Court to a risk of Judicial Review if they erred.