No one-size-fits-all answer exists. Every state has its own time limits, called statutes of limitations, and even within a state the period of time within which you must file a lawsuit varies according to the type of claim.
For example, rules in one state may allow a plaintiff with a personal injury claim (such as a broken leg) one year from the date of injury to file suit and a plaintiff with a breach of contract claim (such as failure to make good on a promissory note) four years from the date of breach to sue. In another state, personal injury plaintiffs may have two years to sue, and plaintiffs with breach of contract claims may have five years.
For various statutes of limitations in your state, see Chart: Statutes of Limitations in All 50 States. Consider consulting a lawyer if you might have a claim or someone might have a claim against you; the rules can be complex.
Once you've figured out what statute of limitations applies to your case, your next step is to determine when the clock starts ticking. In most situations the time starts to run on the "date of harm" -- that is, on the date when you were injured, your property was harmed, or a contract or agreement was violated.
However, a huge exception to this general rule exists. The exception protects plaintiffs in situations where they may not be aware for months or even years that they have been harmed. In such situations, statutes of limitations may start the clock ticking either on the "date of discovery" of the harm or on the date on which the plaintiff "should have discovered" the harm. In short, for some types of legal actions the statute of limitations clock can start ticking at three different times!
(The complexity of the law is a reason to consider consulting a lawyer about exactly how long you have to pursue a lawsuit—and what kind of lawsuit(s) you can pursue.)
Example 1: On January 1, a doctor performs a gallbladder operation on Phoebe but mistakenly removes Phoebe's spleen. The doctor tells Phoebe of the screwup as soon as she wakes up. Phoebe's time period for suing the doctor begins to run on January 1, since the harm occurred on that date and Phoebe actually knew about it. If a two-year statute of limitations for medical malpractice applies to Phoebe's case, she'd have two years from January 1 to file a lawsuit against the doctor.
Example 2: Same case, except the doctor tells Phoebe nothing of the surgical screwup. Phoebe is in constant pain following the January 1 surgery. A month later, on February 1, Phoebe talks to another doctor who tells her that she should not be in pain and that she should immediately come in to have it checked out. Phoebe delays going to the doctor until July 1 of the same year, at which time she finds out that her spleen had been removed mistakenly on January 1. In this situation, Phoebe's time period for suing the doctor probably begins to run on February 1, because the pain coupled with the second doctor's advice determines when Phoebe reasonably should have discovered the harm.
Example 3: Same case, except that Phoebe suffers no unusual after-effects following the January 1 surgery. Phoebe is unaware that anything went wrong with the surgery until July 1 of the same year, when an X-ray during a routine medical checkup reveals that her spleen was removed. In this situation, since Phoebe did not discover and could not reasonably have discovered the harm until July 1, most states would measure Phoebe's time to sue from July 1.
No, but statutes of limitations generally allow at least one year. Except for when you sue a government agency, you almost always have at least one year from the date of harm to file a lawsuit, no matter what type of claim you have or which state you live in. In short, you should have no statute of limitations worries if you sue within this one-year period.
Example: Henry is injured in an auto accident on February 1. On March 1 of the same year, a lawyer whom Henry hires recommends that he seek compensation for his injuries from the driver of the other car. Henry spends months trying to settle with the other driver's insurance company. Finally, on September 1 of the same year, the insurance company writes to Henry that "We'll pay you $1,000, nothing more." Henry concludes that the offer is grossly inadequate and decides to sue the other driver. If Henry isn't sure of his state's statute of limitations for personal injury cases, he should be sure to file the suit by February 1 of the next year and his complaint will definitely be timely.
For various statutes of limitations in your state, see Chart: Statutes of Limitations in All 50 States.
Once you file a complaint on time, a statute of limitations has nothing to do with how long it takes for a case to conclude. However, most states do have separate "diligent prosecution" statutes, which require you to move your case to trial within a certain time period or face dismissal.
An experienced lawyer should be able to explain the ins and outs of the timing issues involved in your case.
No, judges rarely throw out late claims on their own. Defendants must bring to the court's attention any statute of limitations violation.
To be sure that a judge dismisses an untimely case, you include an "affirmative defense" in your answer, alleging that the plaintiff's complaint is untimely. As an alternative to filing an answer, in some courts you can file a Motion to Dismiss, asking a judge to throw out an untimely complaint.
If you are a defendant who thinks that the plaintiff may have waited too long to sue, you'll need to check the applicable state or federal limitations period to determine whether the lawsuit is timely. (You might want to speak to an experienced lawyer, who should be able to explain this complicated area of law.)
For more information on statutes of limitations, see Everybody's Guide to Small Claims Court, by Ralph Warner (Nolo).
Often you cannot sue a government agency unless you first file an administrative claim with the city, county, or state of which the agency is a part. And you may have as little as 60 days to submit an administrative claim. If (as usually happens) the government denies your claim, the denial letter will tell you how long you have to file a lawsuit in court. Check your state's rules quickly after you suffer harm, and consider talking to an attorney for a full explanation of the relevant time periods.
Below you'll find California's statutes of limitations for several common types of lawsuits. These are just broad overviews. Be aware that the law changes and that the rules can be more complex than they first appear. An experienced lawyer should be able to explain the relevant law as it applies to your situation.