If law is exacting, and judges are appointed based on ability to interpret...?

Knowledge of the law is essential. But it is not enough.

Let's say a law exists which reads: "Anyone who eats more than two bowls of oatmeal in the morning is guilty of a misdemeanor." Yes, it's silly, but it's non-political and thus useful as an example.

Does it matter how large the bowls are? Is a person who eats three 4oz bowls guilty, but a person who eats only two 40 oz isn't. Even though one person ate 12 ounces versus the other 80 ounces?

And does morning include pre-dawn? Anything after midnight? Or just dawn until noon? And what if they start eating before noon, but continue after noon? Is that still morning?

I could go on, but you see the point. Laws need to be interpreted. That's the job of judges. And different people can interpret things differently based purely on the way they process information, without any political agenda.

Let's say one judge says the intent of the law, based on legislative history, is to prevent people from eating too much because of the nationwide oatmeal shortage. In this case, the total volume eaten might be more important than whether the individual bowls were large or small. So, the judge would consider a 'bowl' to be a standard unit of amount (say 8 ounces) and interpret the law to be anything over 16 ounces (two units of 8).

A different judge, who happens to be a literalist, says that the size of the bowls doesn't matter. Two bowls means two bowls. So, in the example above, the person who ate 12 ounces in three bowls would be guilty, but the person who ate 80 ounces in two bowls wouldn't be. That's a literal interpretation.

Or let's evaluate the law, in a trial where someone ate one bowl threw it up, ate a second, threw it up, and then ate a third. Does it matter that the person only effectively ate one bowl by the end of the process? Or is it a literal eating of three bowls, regardless of whether they stay down. Different judges could come to different conclusions again.

Many completely different interpretations, without any political agenda. That's why judges can disagree. It's not just a matter of having an opinion. It's how judges interpret the law based on skill, experience, and their particular understanding of how the law should work.

Now tell me. If the law says "no limits should be placed on speech or the press" at a time where there is no radio, TV, film, email, tape recorders, phones, etc. -- should the law be limited only to actual live verbal speech? Or should it apply to sign language? Or signs? Or recorded speech? Or transcriptions of verbal speech? Who is the press? Anything written? Or just written and published by a commercial company? Physically printed, or electronic? And so on...

Huge differences in possible effects, based on how the law is interpreted. And that's just evaluating the effects of 200+ years of technology on a process that hasn't fundamentally changed in thousands of years.

How many possible differences in interpretation can you have when the very structure of a system or the essential values of a culture have changed? Of course you're going to end up with different interpretations based on the same text. Especially if that original text is vague or uses terminology that has changed since it was originally written.

That's why we have judges, and why we have precedent, and why precedent can be overturned as things change.

Because everyone has their own opinion and their own interpretation of what they read. After all, some judges claim the constitution guarantees "the right of privacy" and "the separation of church and state". The fact is that the U.S. Constitution says neither. It's not the law that isn't exacting; its the agenda of judges that is far from exacting.

Because judges interpret the law differently. It is no different in the supreme court.

Where did you get the idea that judges were appointed based on ability?