Call it a petition or call it a complaint. Either way, it is the legal document that starts a new lawsuit. A complaint and a response to the complaint are termed pleadings in the law. Most states offer form pleadings that you fill in and file with the court clerk, such as form complaints for personal injury cases and for breach of contract suits. Even though using form pleadings make the process easier, you still have to figure out exactly whom you are suing, how much time you have to file the complaint and where to sue.

Whom to Sue

If you are filing for divorce, you may not have to ponder long about the name of the defendant, or respondent, in your divorce petition. However, if you slipped and fell in a store, it's a different question. In that case, you'll need to find out who owns the store. If the owner is a company rather than an individual, you'll need to know who owns that company and its legal name before you file the petition.

When to File the Complaint

Although you can file a divorce petition at any point during a marriage, this is not true if you plan to file a complaint because someone's conduct injured you. States impose time periods in which to bring lawsuits, and if you wait too long, you can lose your opportunity to sue. These time periods are called statutes of limitations. Each state determines its own statutes of limitations, and they vary depending on the type of action. For example, in California, you have three years after a car accident to bring a complaint for property damage, but only two years to sue for personal injuries.

Where to Sue

Courts must have personal jurisdiction over the person or business being sued. That means the defendant must have enough contact with the state to make it fair for him to be sued there. Generally, a court has personal jurisdiction over -- and you can sue -- a person who lives in the state or a business entity that does business in the state.

You can also sue an out-of-state defendant if he caused an auto accident in your state. Likewise, you can sue someone in your state if you serve them with the complaint and summons while they are visiting in your state. You can also sue an out-of-state person or business if that person or business has a small, but significant, contact with the state. For example, a business headquartered in a neighboring state that mails sales catalogs into your state to solicit business.

How to Sue

Select an appropriate form complaint for your situation, whether a divorce, personal injury or contract claim. Fill out the form complaint, insert your name as plaintiff and the person or business entity you are suing as defendant. Precisely describe the events that occurred and caused you harm, where and when they took place and how you were injured. Sign and date the complaint.

Fill out a form summons with the names of all parties, and ask the court clerk if there are any other local forms you need to prepare and file at the same time. Make several copies of the documents, file the originals, have the copies stamped by the clerk and pay the court filing fees.