493 A.2d 946 (Del. 1985)
The case of Unocal v. Mesa Petroleum represents a landmark decision in corporate law, specifically concerning the responsibilities of a board of directors when faced with a hostile takeover.
Whether the defensive measures employed by Unocal were reasonable and proportional to the threat posed by Mesa Petroleum's takeover bid?
Directors' decisions in response to a takeover offer must be reviewed under the two-prong Unocal test: (1) the directors must demonstrate that they had reasonable grounds for believing that a threat to corporate policy and effectiveness existed, and (2) the defensive measure must be proportional to the threat posed.
The court held that Unocal's defensive strategy was legal, as it met both prongs of the Unocal test. The board had acted with reasonable grounds to perceive a threat to the corporation, and their response was proportional to the perceived threat.
This case is pivotal for students of corporate law as it articulates the standards under which defensive tactics in hostile takeovers will be evaluated. The 'Unocal test' introduced in this case is crucial for understanding how courts balance the protection of shareholder value with the discretion afforded to boards of directors.