"The Law" is a complex often contradictory abstract rubric that has to be applied to individual circumstances based on incomplete information by imperfect people. That's the whole reason we have both a prosecutor and defense, plus an (ostensibly) impartial judge to adjudicate procedure and a jury to determine guilt/innocence and sentence.

If you could just put data into a computer and have it spit out perfect verdicts, the entire judicial system would be unnecessary.