Final answer:
Cosmo could defend against the lawsuit using the Business Judgment Rule by arguing that his plowback of earnings into R&D was made with an informed, good faith belief that it was in the best interest of the corporation and its shareholders, aligning with both the interests of shareholders and stakeholders.
Step-by-step explanation:
The legal theory Cosmo can rely on for his defense against the class action from shareholders alleging violations of duty of loyalty and duty of care may include the Business Judgment Rule. This rule presumes that in making a business decision, the directors of a corporation acted on an informed basis, in good faith, and in the honest belief that the action was in the best interests of the company. Under this standard, the court does not second-guess a business decision if it was made in good faith, with due care, and within the scope of the director's or officer's authority.
Despite arguments for shareholder primacy that executives should prioritize increasing shareholder wealth, Cosmo could contend that his decision to invest in research and development was made with the company's long-term prosperity in mind—a decision that could ultimately benefit the shareholders even though it may not result in immediate dividends. Additionally, under stakeholder theory, it's argued that corporate decisions should take into account the interests of all stakeholders, which could include investing in experimental technologies that may benefit the company, its employees, and the broader society.
It is important to note, Cosmo's decision must have been made with the appropriate level of diligence and oversight to be protected under the Business Judgment Rule. If it turns out that there was a failure to perform due diligence or that the decision was made with gross negligence, then the protection provided by the rule may not apply.