“Trap and trace” sounds like a hidden wire in a rain-soaked alley, but Washington law treats it as a narrow kind of communication tracing. It is usually not about hearing a phone call or reading a message. It is about the outer trail of a communication. A pen register watches what goes out. A trap-and-trace device watches what comes in. The words stay inside the room, but the wet footprints outside the door can still tell a story.
Washington State places this topic in RCW 9.73.260, inside the chapter on violating the right of privacy. That section covers pen registers, trap-and-trace devices, and cell site simulator devices. Washington is not a bare federal-copy state here. Its statute adds a probable-cause layer, strict order contents, 60-day limits, extension rules, emergency use rules, provider help, deletion rules for cell site simulator data, and a bar on using these tools to investigate criminal liability tied to protected health care services that are lawful in Washington.
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What a Pen Register Does
Washington defines a pen register as a device that records or decodes electronic or other impulses that identify the numbers dialed or otherwise transmitted on the telephone line where the device is attached. The definition excludes ordinary provider or customer devices used for billing, billing records, cost accounting, or similar work in the ordinary course of business.
In plain English, a pen register asks: who did this line reach out to? It looks outward from the targeted line. It should not record the call itself. It should not capture the spoken words or read a message body. It is meant to collect number and signal data, not the conversation.
Think of it as someone watching outgoing envelopes at a mail counter. They can see the address and the time the envelope leaves. They cannot open the envelope and read the letter. Even then, a stack of envelopes can reveal habits, repeated contacts, and timing.
What a Trap-and-Trace Device Does
A trap-and-trace device works in the other direction. Washington defines it as a device that captures incoming electronic or other impulses that identify the originating number of an instrument or device from which a wire or electronic communication was transmitted.
In simple English, it asks: who reached in? It can help identify where an incoming communication came from. A trap-and-trace device follows the trail back toward the caller or sender, but it should not open the message itself.
Picture a cabin road after a long Pacific Northwest rain. A pen register reads tire tracks leaving the cabin. A trap-and-trace device reads tire tracks coming toward it. Neither one steps inside and listens at the table.
Washington Also Covers Cell Site Simulator Devices
Washington’s statute does more than cover pen registers and trap-and-trace devices. It also covers cell site simulator devices. These tools are sometimes called IMSI catchers or Stingray-type devices. They can mimic or interact with cell towers and communication devices to identify, locate, track, or affect a phone or similar device.
Washington defines cell site simulator device broadly. The definition includes tools that identify or track a communication device, obtain communications, stored data, or metadata, affect hardware or software operation, force transmissions or connections, deny access to networks or services, or spoof a communication device, cell tower, cell site, or service.
This matters because a cell site simulator can touch more than a simple number trail. It can sweep up data from nearby devices if not handled tightly. Washington’s statute gives this tool special rules, including data limits and deletion duties.
The General Court Order Rule
Washington law says no person may install or use a pen register, trap-and-trace device, or cell site simulator device without a prior court order under RCW 9.73.260, unless an emergency path or another listed exception applies.
That phrase “no person” matters. It is not aimed only at police. A private person should not secretly trace another person’s calls, account traffic, or phone signals because of jealousy, a breakup, a tenant dispute, a workplace fight, or business suspicion. Paying the bill for a phone or router does not create a private tracing right.
The court order is the gate. Without that gate, a trace can become a trap for the person who set it.
Who Can Apply for an Order?
A law enforcement officer may apply to the superior court for an order or an extension authorizing the installation and use of a pen register, trap-and-trace device, or cell site simulator device. The application must be under oath.
The application must identify the officer making the request and the law enforcement agency conducting the investigation. The applicant must certify that the information likely to be obtained is relevant to an ongoing criminal investigation by that agency.
That is only part of the showing. Washington also requires a probable-cause finding before the court enters the order. This makes the state rule stronger than the basic federal pen-register model, which often turns on a relevance certification alone.
Washington’s Probable-Cause Layer
The superior court must find that the information likely to be obtained is relevant to an ongoing criminal investigation. The court must also find probable cause to believe the device will lead to evidence of a crime, contraband, fruits of crime, items criminally possessed, weapons, or other things by which a crime has been committed or reasonably appears about to be committed.
The court may also issue the order when the device will lead to the location of a person who is unlawfully restrained, reasonably believed to be a witness in a criminal investigation, or wanted when there is probable cause for that person’s arrest.
Probable cause is more than a hunch. It asks for facts that support the request. Washington does not let this tool run on vague interest alone.
What the Order Must Say for Pen Registers and Trap-and-Trace Devices
For a pen register or trap-and-trace device, the order must name, if known, the person to whom the phone line is leased or in whose name it is listed. It must also name, if known, the person who is the subject of the criminal investigation.
The order must state the number and, if known, the physical location of the telephone line where the device will be attached. For a trap-and-trace device, it must also state the geographic limits of the order.
The order must include a statement of the offense to which the information likely to be obtained relates. This keeps the order tied to a case rather than turning it into a wide scan through someone’s contact life.
What the Order Must Say for Cell Site Simulator Devices
For a cell site simulator device, the order must go deeper. It must state the identity, if known, of the subscriber or person whose electronic communication service is being targeted. It must also state, if known, the person who possesses the device to be targeted.
The order must include the telephone number or other account number for the service, the physical location of the device if known, the type of device, and the communication protocols being used. It must also state the geographic area covered by the cell site simulator.
The order must list all categories of metadata, data, or information to be collected from the target device, including call records and geolocation information. It must also say whether information from devices not named in the order will be incidentally collected, what categories may be collected, and whether any network access or internet access disruption may occur.
How Long a Washington Order Lasts
An order for a pen register or trap-and-trace device may last no more than 60 days. An order for a cell site simulator device also runs for 60 days.
An extension requires a new application. The first extension may be granted only with a showing that the information or items sought are more likely to be obtained under the extension than under the original order.
Further extensions face a higher gate. The state must show a high probability that the information or items are much more likely to be obtained under the second or later extension than under the original order. There must also be extraordinary circumstances, including a direct and immediate danger of death or serious bodily injury to a law enforcement officer. Each extension may last no more than 60 days.
Sealing and Nondisclosure
A Washington order must direct that it be sealed until the court says otherwise. It must also direct the person who owns or leases the line, or the person ordered to help, not to disclose the device or the investigation to the listed subscriber or anyone else unless the court allows it.
This is why a person may not learn about the order while it is active. A provider, landlord, custodian, or other helper may be under a court command to stay silent.
A business that receives such an order should route it to counsel or a trained legal-response person. It should not be copied through casual office messages or discussed with the customer.
Provider, Landlord, and Custodian Help
When the court order directs help, a provider of wire or electronic communication service, landlord, custodian, or other person must furnish the information, facilities, and technical help needed to install the pen register. The work must be done unobtrusively and with minimal service interference.
For a trap-and-trace device, the ordered person or provider must install the device on the proper line and provide added information, facilities, and technical help, including installation and operation. Unless the court orders another method, results go to the officer named in the order at reasonable intervals during regular business hours for the duration of the order.
The helper must be reasonably paid by the law enforcement agency for reasonable expenses. Washington also protects providers and other covered helpers from lawsuits when they give information, facilities, or help according to the court order. Good-faith reliance on a court order, request under the statute, legislative authorization, or statutory authorization is a complete defense.
Emergency Use
Washington has an emergency path. A law enforcement officer and a prosecuting attorney or deputy prosecuting attorney may jointly and reasonably decide that probable cause supports emergency use. The emergency must involve immediate danger of death or serious bodily injury, and it must require installation and use before an order can be obtained with due care.
There must also be grounds on which a court order could be entered. If emergency use begins, a court order approving the installation or use must be issued within 48 hours after installation has occurred or begins to occur.
Without an approving order, use must stop when the information sought is obtained, when the application is denied, or when 48 hours pass, whichever comes first. If the order is not obtained within 48 hours, the information is not admissible in any legal proceeding.
Emergency Reporting and Penalties
If a law enforcement officer knowingly installs or uses a pen register, trap-and-trace device, or cell site simulator device under the emergency rule without applying for the authorizing order within 48 hours, that conduct is a violation of the chapter and is punishable as a gross misdemeanor.
A law enforcement agency that authorizes emergency installation must file a monthly report with the administrator for the courts. The report must state the number of emergency authorizations, date and time of each authorization, whether court approval was sought within 48 hours, and whether approval was granted.
That monthly report rule makes emergency use less like a dark tunnel and more like a tunnel with a counter at the end. The court system gets a record of how often the emergency door was used.
Cell Site Simulator Data Limits
A law enforcement agency using a cell site simulator device must take steps to limit collection to the target named in the court order. It must delete information or metadata collected from a person or device not named in the order right after collection. It may not transmit, use, or keep that outside information for any purpose.
The agency must also delete information or metadata collected from the named target within 30 days if there is no longer probable cause to believe the information or metadata is evidence of a crime.
Washington also has RCW 9.73.270, which says the state and its political subdivisions may not collect or use a person’s electronic data or metadata by means of a cell site simulator device without informed consent, a probable-cause warrant that particularly describes the person, place, or thing to be searched or seized, or a recognized exception to the warrant requirement.
Protected Health Care Services Limit
Washington adds a special shield for protected health care services. If an application seeks information tied to an investigation alleging criminal liability for providing, receiving, attempting to provide or receive, assisting in, or attempting to assist with protected health care services that are lawful in Washington, the applicant must say so under penalty of perjury.
The court may not issue an order for a pen register, trap-and-trace device, or cell site simulator device for the purpose of investigating or recovering evidence tied to criminal liability for protected health care services that are lawful in Washington.
This rule acts like a locked gate around lawful Washington health care activity. It stops these tracing tools from being used as a back road into certain out-of-state criminal investigations when the care is lawful in Washington.
How This Differs From Wiretapping
Washington’s general recording and interception rule appears in RCW 9.73.030. Washington is known as an all-party consent state for many private communications and conversations. As a starting point, private telephone communications and private conversations may not be recorded without the consent of all participants unless a listed exception applies.
That is different from a pen register or trap-and-trace device. Wiretapping or recording reaches the communication itself. A pen register or trap-and-trace device should deal with outside information: numbers, origin, destination, timing, and signal data.
The difference is like reading a package label instead of opening the box. Trap-and-trace law studies the label. Wiretap and recording law deals with opening the box.
One-Party Recording Exceptions Are Not a Trace License
Washington has exceptions that allow one-party recording in some settings, including emergency communications, threats, anonymous or repeated calls, and calls at extremely inconvenient hours. There are also special rules for certain law enforcement recordings connected to controlled substances and commercial sexual abuse of a minor.
Those recording exceptions do not give private people a broad right to trace someone else’s line, account, router, or phone. Recording a call under a narrow exception is one question. Installing or using a pen register, trap-and-trace device, or cell site simulator is another.
Do not mix the two. A person can be wrong under the tracing statute even if they think a recording rule helps them.
Private People Should Not Try This
A private person should not install hidden software, hardware, router rules, call-forwarding settings, spyware, account filters, or tracing setups to follow someone else’s communications. Suspicion is not enough. A breakup is not enough. A business fight is not enough. Paying the phone bill may not be enough.
Do not log into another person’s account to learn who contacted them. Do not hire someone to trace calls or messages outside lawful process. Do not place monitoring equipment on a phone line, router, laptop, office system, shared account, or phone for personal reasons.
Washington’s privacy chapter, the Washington Cybercrime Act, stalking law, computer trespass law, civil claims, workplace rules, family-court orders, and federal pen-register law can all enter the room. A secret trace can turn into a legal pit.
Employers and Business Systems
Employers often keep phone logs, email routing logs, network logs, access records, security alerts, billing data, and fraud records. Some logging may be ordinary business activity when tied to service upkeep, security, billing, fraud control, or abuse response.
But secret tracing of private communications can create legal risk. Company ownership of a phone, laptop, router, email account, or work system does not answer every question. Written policy, notice, consent, business need, data type, and access limits all matter.
A Washington employer should get legal review before adding systems that trace worker communication patterns beyond ordinary business logging. The safer route is written policy, narrow collection, limited access, and clean records.
Website Tracking and New Data Questions
Pen-register and trap-and-trace ideas began in the phone world, but newer disputes can involve websites, apps, analytics scripts, chat boxes, ad pixels, device IDs, IP logs, and account tracking. These systems can send user activity to outside vendors with little visible sign on the screen.
Not every web-tracking dispute is a Washington pen-register case. Some turn on wiretap law, consumer protection law, contract terms, health data, consent banners, account notices, or how data moves to a vendor.
Washington businesses should review tracking systems before launch. A small script can act like a keyhole if it passes too much user activity to the wrong party.
What Washington Residents Should Know
For Washington residents, the practical point is that law enforcement may seek a superior court order for live tracing tools during an ongoing criminal investigation. The target or subscriber may not receive notice while the order is active because sealing and nondisclosure rules apply.
The data may later appear in warrant papers, charging records, discovery, or motion practice. It may show outgoing contacts, incoming origins, timing, geolocation information in cell-site-simulator cases, or other device data. Even without spoken words, that data can carry force.
If you learn that one of these orders was used in a case involving you, a Washington criminal defense lawyer can review the application, probable-cause showing, order, dates, extension papers, provider returns, emergency claim if any, deletion duties, and whether the data stayed inside the court-approved boundary.
What Providers and Businesses Should Do With an Order
A provider, landlord, custodian, platform, or business that receives a Washington order should treat it as legal process. Preserve the document. Limit internal access. Send it to counsel or a trained legal-response person.
Read the order closely. Check the court, date, covered telephone line or device, physical location if listed, data type, geographic limits, time period, named officer, assistance language, sealing language, and nondisclosure command. Provide what the order requires, not extra data from extra accounts or extra dates.
Keep a clean record of the response. Note when the paper arrived, who reviewed it, what help was given, what data was furnished, and when. A careful response is like tying down a tarp before a coastal wind. It keeps the matter from tearing loose later.
Common Misunderstandings
One common misunderstanding is that trap and trace means listening to calls. It does not. It points to incoming identifying data, not the words spoken.
Another misunderstanding is that Washington uses only a federal-style relevance rule. Washington requires relevance to an ongoing criminal investigation and a probable-cause finding tied to evidence, contraband, crime-related items, weapons, certain locations of people, or an arrest basis.
A third misunderstanding is that cell site simulators are just pen registers with a new name. They are broader tools, and Washington gives them added order details, warrant or consent rules for electronic data and metadata, and deletion duties.
A final misunderstanding is that private people can trace communications if they own the account. Ownership alone is not a court order, and it may not be consent.
Bottom Line on Washington Trap and Trace Law
Washington trap and trace law centers on RCW 9.73.260. A pen register records or decodes outgoing number data. A trap-and-trace device captures incoming impulses that identify the originating number. The same section also covers cell site simulator devices, which can identify, locate, track, collect data from, or affect communication devices.
No person may install or use a pen register, trap-and-trace device, or cell site simulator device without a prior court order under the statute, unless an emergency path or listed exception applies. A law enforcement officer may apply under oath to superior court. The application must identify the officer and agency and certify relevance to an ongoing criminal investigation. The court must also find probable cause under the statute before issuing the order.
The order must name known subscribers, known investigation subjects, covered lines or devices, physical locations if known, trap-and-trace geographic limits, cell-site-simulator data categories when applicable, and the offense tied to the information sought. A pen-register or trap-and-trace order may last no more than 60 days. Cell site simulator orders run for 60 days. Extensions face stricter showings, and later extensions require extraordinary circumstances.
Orders are sealed and include nondisclosure commands. Providers and other helpers must assist when ordered, must be reasonably paid, and receive protection for compliance. Emergency use requires a joint reasonable determination by law enforcement and a prosecutor, a 48-hour court-approval deadline, and monthly reporting. Cell site simulator use carries added data-limiting and deletion duties. Washington also bars these tools from being used to investigate criminal liability tied to protected health care services that are lawful in the state. The law does not open the letter, but it can study the envelope. In Washington, that envelope sits behind a strong court gate.