Usually when someone says "breaking the law", they're referring to a crime, so you're correct.
A board which fails to act in a way which maximizes shareholder value, when that is the stated goal of the corporation (as it often is), is in breach of its fiduciary duties, which is a civil offense.
A board which fails to act in a way which maximizes shareholder value, when that is the stated goal of the corporation (as it often is), is in breach of its fiduciary duties, which is a civil offense.