An LLC’s operating agreement is the document that decides almost every dispute that follows, and default statutory rules apply wherever it is silent. Most disputes between members trace to a gap rather than to a term.
The provisions that get litigated
Management. Member-managed or manager-managed, and what each may do without consent. The list of decisions requiring a supermajority is where control actually lives.
Distributions. Whether they are mandatory, discretionary, or tied to tax liability. A member facing a tax bill on allocated income with no distribution to pay it is one of the commonest grievances in the field.
Capital calls. Whether members can be required to contribute more, and what happens if they will not — dilution, a loan, or nothing.
Transfers. Whether an interest can be sold, to whom, and what a transferee gets. In most states a transferee who is not admitted as a member receives economic rights only, and no vote or access to information.
Exit. Whether a member can withdraw, and what they receive if they do. Many statutes give no exit right at all by default, which is how people end up locked into companies they want to leave.
Deadlock and dispute resolution. See the note on deadlock.
Two things worth adding
A clear statement of what the members expect of each other — the informal understandings about employment, salary and role that a court would otherwise have to reconstruct from conduct years later.
And a mechanism for valuing an interest, agreed while everyone is still on good terms. Valuation is the most expensive part of nearly every owner dispute, and it is far cheaper to agree the method in advance than the number in hindsight.