Business Associations
Agency
Agency requires consent, benefit to the principal, and control. Authority may be actual (express or implied), apparent (based on the principal's manifestations to a third party), or conferred by ratification. Agents owe fiduciary duties of loyalty and care; principals owe duties to indemnify and reimburse.
Partnerships and LLCs
Under RUPA, each partner is an agent of the partnership, and the partnership is liable for obligations incurred in the ordinary course; partners are jointly and severally liable for partnership obligations. Dissociation triggers a buyout. LLCs give members limited liability, with management by members or by designated managers under the operating agreement.
Corporations
Formation by articles of incorporation; de facto corporation and corporation by estoppel survive in a few states. Veil piercing applies for alter ego, undercapitalization, or fraud. Directors owe care and loyalty; the business judgment rule presumes informed decisions by disinterested directors. Self-dealing triggers entire fairness review unless approved by disinterested directors or shareholders. Controlling shareholders owe fiduciary duties to minority holders.
Shareholder litigation
Derivative suits require demand on the board or demand futility plus contemporaneous ownership. Direct suits redress injuries to shareholders personally.
Worked example
A CEO steers a contract to her brother's company without disclosure. The business judgment rule does not apply; she bears the burden of proving entire fairness, and the transaction may be voidable.
Rule of thumb: ask who owes the duty, to whom, and whether the business judgment rule displaces review.