You can sue someone whose address you don’t know, but the court won’t let the case move forward until the defendant has been formally notified, and that takes extra work on your end. The path is: file the complaint, run a documented search for the person, and if the search fails, ask the judge for permission to notify them through an alternative method like newspaper publication, email, or social media. It adds time and cost, and a judgment obtained this way is easier for the defendant to challenge later.
Why the Address Matters at All
Courts can’t rule against someone who hasn’t been told they’re being sued. That notice is called service of process, and it exists because the Constitution’s due process protections prohibit courts from exercising power over a defendant who hasn’t been given the chance to respond.1Legal Information Institute. Service of Process The usual method is physically handing the defendant a copy of your complaint and a court-issued summons.2Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons If service isn’t valid, the defendant can get the entire case dismissed.
The Supreme Court’s standard, from Mullane v. Central Hanover Bank, is that notice must be “reasonably calculated, under all the circumstances, to apprise interested parties of the pendency of the action and afford them an opportunity to present their objections.”3Legal Information Institute. Mullane v Central Hanover Bank and Trust Co That phrase becomes the yardstick when you ask a court to approve an unusual service method.
Start Your Own Search First
You don’t need the defendant’s address to file the complaint. Draft it, get the summons issued, and start looking. Filing first stops the statute of limitations clock and gives you standing to use litigation-specific tools discussed below.
Cheap and fast methods come first:
- Public records. Property tax rolls, voter registration, prior court filings, and business entity records on file with the Secretary of State often list current or recent addresses. Most counties and states put these online for free.
- Online searches. A search engine query with the defendant’s name plus an employer, city, or profession sometimes surfaces an address directly. Social media profiles carry location tags, employer info, and check-ins. People-finder sites aggregate public records for a small fee.
- Informal contacts. Former coworkers, past landlords, mutual acquaintances, and family members sometimes know exactly where the person is and are willing to say so.
- Professional licensing boards. If the defendant holds a state license — contractor, nurse, real estate agent, and so on — the licensing agency usually publishes the licensee’s address of record.
Log every step: the date, what you searched, what came back. That log becomes evidence later when you ask the judge to approve a nonstandard service method.
Government Records You Can Tap
USPS Forwarding Addresses
The Postal Service keeps forwarding-address records when someone files a change of address. Process servers, attorneys, and self-represented litigants involved in actual or anticipated litigation can request that information under federal regulation 39 CFR 265.6(d)(5)(ii). You submit the defendant’s name and last known address, the court where the case is or will be filed, and the names of all known parties. Putting false information on the request is a federal offense punishable by fines up to $10,000 or up to five years in prison.4United States Postal Service. Change of Address or Boxholder Request Format – Process Servers
DMV Records
State DMVs are barred by federal law from casually releasing personal information from motor vehicle records. The Driver’s Privacy Protection Act carves out an exception for use in connection with civil, criminal, or administrative proceedings, which includes service of process and pre-litigation investigation. Licensed private investigators can also pull DMV records for any purpose the statute allows.5Office of the Law Revision Counsel. 18 US Code 2721 – Prohibition on Release and Use of Certain Personal Information From State Motor Vehicle Records Each state runs the request process differently, so check with the DMV in the state where the defendant likely holds a license.
When to Hire a Private Investigator
If your own searches stall, a licensed investigator can reach further. They have legal access to DMV records under the DPPA, subscribe to skip-tracing databases that cross-reference credit headers, utility hookups, and public records, and can do fieldwork to chase down partial leads. Fees run from a few hundred dollars for a straightforward name-and-last-city search to several thousand for defendants using aliases or actively hiding. If you already have a lawyer, ask before hiring separately: many firms have their own investigators or database subscriptions.
Documenting a Diligent Search
A judge won’t authorize alternative service on your say-so. You have to show what courts call a “diligent search,” and the bar is higher than most people expect. “I looked online” is not enough.
Requirements vary by jurisdiction, but a typical checklist covers postal forwarding records, the defendant’s last known employer and any W-2 or pension mailing addresses, professional licensing agencies, telephone directories for the last known area, DMV and law enforcement records, property tax and tax collector records, internet and social media searches, and inquiries to relatives and known associates. Some courts also want to see checks with the Department of Corrections, military records, hospitals, and utility companies in the last known area.
You put this all in a sworn declaration or affidavit listing each source, the date you checked it, and what you found. The judge reads that document and decides whether you’ve done enough. Skipping steps here is a common reason motions get denied — and a common reason default judgments get thrown out down the road.
Asking the Court for Alternative Service
Service by Publication
Publication means running a legal notice in a newspaper of general circulation. Courts treat it as a last resort because almost no one reads legal notices.6Legal Information Institute. Service by Publication If a judge approves it, you’ll typically run the notice once a week for a set number of consecutive weeks, often three or four depending on jurisdiction. Costs range widely. Legal notice rates are often set by state statute and calculated per word, line, or square inch. A short notice in a small-market paper can be under $100; a longer notice in a major metro paper can top $1,000. Ask the newspaper’s legal advertising department for a quote first.
After the run ends, the newspaper issues an affidavit of publication, which you file with the court as proof of service.
Substituted Service
If you have a current address but can’t catch the defendant there, substituted service lets you leave the papers at the defendant’s dwelling or usual place of abode with someone of suitable age and discretion who lives there.2Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons You can also serve an agent the defendant has authorized to accept process.7Legal Information Institute. Substituted Service The person accepting the documents has to actually live there. Leaving papers at a stale address won’t survive a challenge.
Email, Text, and Social Media
When you can’t find a physical address but have digital contact points, you can file a motion asking the court to authorize service through those channels. Judges have approved service by email, text message, Facebook, Twitter, and messaging apps like WhatsApp. In one federal case, the court authorized service “through every known internet account, including but not limited to: e-mail, text message, iMessage, WhatsApp, and Twitter” after the plaintiff’s search for a physical address failed.
To win this motion you have to show two things: a diligent search that came up empty, and that the proposed channel is reasonably likely to actually reach the defendant. For social media that means proving the account is active. A dormant profile from three years ago won’t persuade most judges. Recent posts, a message the defendant sent you through the platform, or other evidence of current use is what carries the motion.
If the Defendant Is a Business
Suing a company makes the address problem much smaller. Every state requires registered business entities to designate a registered agent for service, and the agent’s name and address are public record through the Secretary of State’s office. Most states offer a free online lookup. If the business has let its registered agent lapse, many states let you serve the entity through the Secretary of State directly, which then forwards the papers to the last known address. Officers and managers — a corporate president, a general partner — can also generally be served as agents of the entity. Sole proprietors and unregistered businesses fall back on the individual-service rules described above.
Deadlines That Can End the Case
Two clocks run while you’re searching.
The statute of limitations is the deadline to file the lawsuit at all. In most jurisdictions, filing the complaint stops that clock even before service, but confirm the rule where you’re filing.
The service deadline is separate. In federal court, you have 90 days after filing to serve the defendant. Miss it and the court must dismiss without prejudice unless you show good cause.2Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons “Without prejudice” means you can refile, but if the statute of limitations expired in the meantime, your claim is gone. State courts set their own service deadlines.
If the search is dragging, file a motion to extend the service deadline early. Don’t wait until day 89. Judges are much more willing to help plaintiffs who flag the problem before it becomes a crisis and can show real effort in the meantime.
A Publication Judgment Can Come Undone
Serve someone by publication and they almost certainly won’t see it, won’t respond, and you’ll win by default. That win is fragile. A defendant served by publication can come back months or years later and move to vacate the judgment on the ground that they never got actual notice. Federal rules let a party seek relief from a judgment for mistake, excusable neglect, or other reasons within a reasonable time, and many states give defendants served by publication an even wider window.
This matters most when the judgment touches real property, custody, or serious money. If you’ve collected on the judgment or relied on a custody order, having it vacated unwinds everything you built on top of it. Before choosing publication, weigh whether the resulting judgment is worth the effort given the real chance it gets overturned. Sometimes patience — continuing the search for a real address — produces a more durable result than rushing through the notice pages of a newspaper.