Withholding information that you know the answer to in a court of law is the same as lying. The result is the same. You are punished for it. The lie is called perjury and you are held in contempt of court fot it. Refusing to answer is showing your contempt for the court. You are punished for it. In both cases, you have failed to answer a question from a truth seeking authority. Many Jehovah's Witnesses have had their consciences dulled by their blind devotion to a less than honest organization.
The Jehovah's Witnesses have used the Courts extensively in their efforts to legitimize their religion. Truth in a court of law, as elsewhere in life, is paramount.
By being truthful in all things and to everyone we show that we are true christians. Jehovah's Witnesses teach wait on Jehovah for other things, why not tell the truth at all times and use the wait on Jehovah doctrine?