Textbook discussions of personal jurisdiction are usually about potential jurisdiction. However, before a court can enter an effective judgment, it must have actual jurisdiction over the person against whom the judgment is rendered. Residence, presence, and long- arm statutes make it possible for a court to obtain actual jurisdiction over individuals and entities. Actual jurisdiction is obtained by "service of process" on a person or entity.

In this context "process" is usually a Summons and a copy of the plaintiff's Complaint. Most courts' rules provide that delivery of a Summons, by itself, is sufficient. However, most courts' rules also require that the plaintiff supply the defendant with a copy of the Complaint within a relatively short time. Therefore the common practice is to deliver the Summons and the Complaint at the same time. A Summons states that a lawsuit has been (or soon will be) commenced against the defendant in a particular court and gives the defendant a limited time to respond. The length of time allowed varies but 20 days is common if service is made within the court's geographic jurisdiction.

With rare exceptions, service of process can not be accomplished via mail. There is not a sufficient degree of certainty that the specific defendant will actually receive mailed documents. Defendants can agree to accept service by mail, or otherwise. While it is unusual for defendants to agree to accept service, there is usually no good reason why they should not. Trying to avoid service of process is ultimately futile. The court must have some method of obtaining actual jurisdiction over recalcitrant defendants. If it did not, the courts' power could be totally abrogated.

The actual service of process (delivery of the documents) must be done by someone who is not a party to the litigation. Traditionally service has been made by the Sheriff or Marshal. Most states now allow service by private individuals and there are companies that make that a business. Being a process server is not a particularly safe occupation.

The most effective kind of service of process is personal service. That means that the documents are actually physically delivered to the person(s) named as defendants. The process server has a great deal of latitude. It is okay to use fraudulent means to accomplish service. For example, a process server might put a Domino's Pizza sign on his or her car, dress up in the appropriate uniform and announce that he or she is there to deliver a pizza. It is also not necessary that the defendant physically accept the documents or acknowledge their receipt by signing anything. If the defendant refuses to open the door, the process server can push the papers through the mail slot. If the defendant is standing at the window looking out, the process server can tape the papers to the window. The only requirement is that the process server be able to honestly say that the defendant was made aware that the papers were being delivered to him or her. Personal service can be accomplished anywhere — home, store, work, alongside the freeway, etc.

The next-most-effective, and perhaps the most frequent, is substitute service. That requires the papers to be actually delivered (1) at the defendant's normal place of abode, (2) to someone of "suitable age and discretion." The papers can be delivered to anyone at the house, even someone who does not live there. The recipient need not be an adult. The process server should, however, only deliver the papers to someone who will probably pass them on to the proper person. Service would not be adequate if the papers were given to a 5-year-old child or the dog.

If neither personal nor substitute service is possible, a defendant can be served by publication. This usually requires the court's prior approval, which will be given only if the plaintiff has reasonably tried and failed to obtain service or if it is obvious that those efforts will prove fruitless. Service by publication requires publication of the summons in a newspaper. Usually there are "official" newspapers and one of them must be used. In larger cities, there are "legal" newspapers that do little more than publish lists of judgments, court filings, deed filings, summonses, and the like. Very few people actually read those newspapers. But the fact that the defendant did not actually read the published summons does not make any difference. Service by publication usually also requires mailing copies, by certified mail, return receipt, to the defendant's last-known address.

If a defendant does not respond after effective service of process, the plaintiff can obtain a "default judgment." If the defendant later learns about the judgment, he or she can request that it be set aside. Of course, the defendant has to have a good reason for not responding. If there was actual personal service, good reasons are hard to find. If service was by "substitute service," the defendant has a slightly greater chance of prevailing, but must show why it was not reasonable to expect her or him to get the papers. For example, the papers were given to a hired to mow the lawn and the defendant was out of town both at the time of service and the following two months. If service was by publication, the defendant needs only to state that he or she did not read that newspaper or actually receive the mailed papers or know of the lawsuit. In each situation, however, the defendant must also show that she or he has a defense of some type — if the defendant has no defense, he is going to lose anyway, so why waste everyone's time. If the court sets aside the default, the case then proceeds normally.

If the defendant is an entity, such as a corporation, there are special rules concerning service. If the entity has an in-state office, service is accomplished by serving an appropriate employee at that office. A secretary or receptionist at the main executive offices is usually adequate. If a defendant entity has no in-state office, service can usually be accomplished by delivery to the Secretary of State, who then forwards the papers to the defendant. All corporations registered to do business in a state must identify a "registered agent." That person or entity must be a resident of, or have offices in, the state.

If a defendant (person or entity) is not a resident of the state in which the litigation is filed, service can be accomplished in the defendant's home state through either personal or substitute service. (This assumes that the long-arm statute of the state where the litigation started authorizes service in the particular case.)