Answer:
Judicial Precedent.
Explanation:
This is the most known method of interpreting the Constitution and it is based on Judicial decisions, and if another case in the future has similar facts, principles, rules, etc. it will use previous decisions to make it easier. So, basically, the interpretation of the Constitution itself becomes a "law", and that is why the Constitution is interpreted as a living document, since judges, lawyers, academics of law etc. are always discussing the interpretation of the situation based on more actual principles than the ones that were considered at the moment of the creation of the Constitution.
