Demurrer (state court) and Motion to Dismiss under Federal Rule of Civil Procedure 12(b)(6) (federal court)
Both of these motions are the legal equivalent of saying "so what?" For example, where a plaintiff files a complaint, the defendant may file a demurrer to the complaint that argues that the plaintiff is not entitled to any relief even if one assumes that all of the allegations of the plaintiff's complaint are true. If a complaint states more than one cause of action, the demurrer may be directed at one or more of the causes of action. A demurrer or motion to dismiss is typically filed shortly after the filing of a complaint for the purpose of attempting early resolution of a case without further expense, eliminating at least some of the causes of action in the complaint, or forcing the plaintiff to amend the complaint with allegations that may state a claim but be more difficult to prove. Consider the following example. Suppose that a customer of See's Candies filed a complaint against See's Candies consisting exclusively of an allegation that she could not determine the filling of a candy by looking at the chocolate coating. A court would sustain a demurrer to that complaint (or, if brought in federal court, would grant a Rule 12(b)(6) motion to dismiss), because the customer has not alleged facts entitling her under the law to some remedy against See's. A plaintiff may also demur to some or all of a defendant's answer, claiming, for example, that allegations in the answer, even if true, do not constitute a legally cognizable defense to the complaint. For example, if a defendant who has been sued for assault files an answer claiming that the assault was justified because the plaintiff's eyes were blue, the plaintiff could successfully demur to that defense in the answer.
Review of lower court decisions by an appellate court is governed by "standards of review." Where a party presents an issue on appeal that the appellate court considers a question of law (e.g. whether the principles of contract law permit a court to find an implied in fact contract between cohabitants concerning distribution of property upon separation, as in Marvin v. Marvin), the appropriate standard of review is de novo review. For de novo review, the appellate court reviews the record of the evidence presented to the lower court to resolve an issue independently (literally "anew" or a second time) of the lower court's resolution of the issue. In contrast, where a party presents an issue on appeal that the appellate court considers a question of fact (e.g. did the cohabitants form an implied in fact contract concerning distribution of property upon separation), the appropriate standard of review is one in which the appellate court will affirm the decision of the lower court based on the appellate court's review of the record unless the decision of the trial court was clearly erroneous.
A judgment on the pleadings is based exclusively on the pleadings in a case (complaint, answer, reply to the answer, if any), i.e. without consideration of any evidence. It is thus similar to a demurrer, except that a demurrer will be to a particular pleading. For example, a defendant may demur to the plaintiff's complaint or may wait until after it files its answer and then file a motion for a judgment on the pleadings. In contrast, a summary judgment (a judgment prior to and without trial) will typically be based both on pleadings and on evidence presented through declarations, admissions, depositions, or interrogatories.
A judgment rendered by the court without trial based upon the matters contained in the pleadings and upon evidence deriving from discovery (admissions, depositions, interrogatories, production of documents), stipulation of the parties, and declarations or affidavits of parties or witnesses under penalty of perjury. See Parker v. Twentieth Century-Fox Film Corp. and Quill v. Newberry for useful discussions of the nature of summary judgment, and disagreement about whether a motion for summary judgment should have been granted in the case. A partial summary judgment (in California now referred to as "summary adjudication") is a summary judgment with respect to some of the issues presented by a case. For example, a court might render a partial summary judgment finding one party liable to another for breach of contract but leave to trial the issue of the amount of damages to be paid for the breach.
A judgment rendered after presentation of some evidence at trial. For example, in Pugh v. See's Candies, after Mr. Pugh had presented all of his evidence at trial and before See's Candies presented its evidence, See's Candies argued that Mr. Pugh's evidence, even if believed, did not give him a right to hold See's responsible for breach of contract.
As you will learn in your course in civil procedure, federal and state constitutions require a trial by jury in many but not all types of cases. Parties who are entitled entitled to trial by jury may waive that right in favor of a trial by judge. Where the parties have waived trial by jury, the judge rules not only on legal issues but also serves as the trier of fact.