Legal Question in Traffic Law in California

You may ask the judge to dismiss the case in the interests of justice. However a case is rarely dismissed pursuant to Penal Code Section 1385. Without knowing more facts I cannot suggest any defenses. You should sit down with an experienced attorney and discuss both the facts and available defenses.

Penal Code 1385 allows a court to dismiss (as the main reason) a case "in the interest of justice".

How do you 'use' it? You don't, techincally. You can ask a judge to dismiss your case, but why would they? What reason is there?

Or are you asking if they will dismiss your case because you think it's weak?

Your question is just too vague to give a quick online answer. If this is a criminal case that's pending in court (or upcoming), you would be well advised to consult face to face with a criminal defense attorney to discuss the facts, any possible defenses and issues.