Ultimate facts are the essential facts that constitute a party's cause of action or defense. A fact is essential if it cannot be removed without making the statement of the cause of action or defense insufficient or inadequate. They are considered the principal, determinative, and constitutive facts upon which an entire cause of action rests. Ultimate facts are also described as important and substantial facts that form the basis of a primary right and duty, or make up the defendant's wrongful act or omission.

Pleadings must contain only ultimate facts, stated plainly, concisely, methodically, and logically. Statements of mere evidentiary facts should be omitted from pleadings. Conclusions of fact or law should not be alleged in pleadings.

In summary:

• Ultimate facts are essential facts of a claim or defense.
• They are necessary because their removal makes the pleading insufficient.
• They are the core facts that establish a cause of action.
• Pleadings should include ultimate facts.
• Evidentiary facts (proof details) and conclusions should be omitted.
• Material allegations, which include ultimate facts, are deemed admitted if not specifically denied.
• In a motion to dismiss, ultimate facts alleged in the complaint are hypothetically admitted.

Examples of the types of material facts that should be clearly and definitely averred in a pleading, as distinguished from mere evidentiary details, include:

• Names of persons involved.
• Names of corporations involved.
• Specific dates relevant to the claims.
• Amounts involved in transactions or damages.
• Specification of property for identification.
• Details of particular transactions, including withdrawals and disbursements.
• Other material facts that support the conclusions and inferences in the complaint.

These details are necessary so the adverse party is fairly informed of the claims and can prepare their responsive pleading and for trial. Failure to allege these specific facts, relying instead on conclusions unsupported by factual premises, can render a pleading deficient.