Borders should be defined strictly. If they are not, the law is faulty and needs to be fixed.
That is precisely what happens when a Judge hands down a decision on a border case. That judgment becomes a precedent which is as good as law in a courtroom unless the previous judgment is overturned. There are too many possible border cases, consider V&T laws, custody battles,corporate fraud, etc...; situations where the human element introduces a mind boggling number of variables. Lawmaker cannot possibly define a law that covers every contingency. That is the Judges job.