Is it legal to collect audio recordings by yourself? Does recording in the office count as a violation of the law? Learn the key tips and techniques for evidence collection—this guide will teach you how to win a legal battle of your own.

“My husband is cheating on me again. I’d like you to send an investigator to help me gather evidence!” — a distressed wife came straight to Yitong Investigation Agency and told us frankly. In fact, this wasn’t the first time her husband had been unfaithful. We had even helped her win several infidelity lawsuits in the past, resulting in substantial settlement payments. Yet, surprisingly, the couple seemed locked in a cycle—one willing to cheat, the other willing to forgive—repeating the pattern of infidelity, investigation, and compensation, as if they were strangely addicted to it.

This time, the client seemed eager to try her hand at playing detective. She even brought in an audio recording she had secretly collected, proudly explaining her method of gathering evidence. However, once we listened to it, we immediately realized that the recording likely violated the law. While a failed investigation is one thing, violating privacy laws and being charged with the crime of infringing on someone’s secrets is far more serious. We urgently warned her to proceed with caution—getting punished instead of receiving justice could turn her from victim to perpetrator in the eyes of the court.

Afterwards, the client asked us: What should I be careful about when collecting evidence on my own? Is secretly recording someone legal? Could it be considered a violation of privacy, rendering the evidence inadmissible? Yitong Investigation Agency reminds all clients: self-collection of evidence involves many legal and technical details. If handled poorly, it could alert the other party and lead to a situation where you not only lose your case, but also suffer additional consequences.

When is evidence collection necessary?

The most common types of cases that require evidence collection include the following:

• Infidelity and violation of spousal rights
• Domestic violence
• Medical disputes
• Water leakage or noise disputes with neighbors
• Traffic accident claims
• Copyright infringement
• Rental disputes
• Fraud
• Threats or intimidation
• Civil litigation
• Criminal offenses
• National compensation claims
• Non-litigious dispute mediation

On-site evidence collection requires the ability to obtain admissible video and audio recordings!? Let the Yitong Investigation team explain!

Probative value refers to whether an "object," "audio recording," or "video recording" can be used as admissible evidence to establish the facts of a crime. According to the legal dictionary, Article 154, Paragraph 2 of Taiwan’s Code of Criminal Procedure states: “The facts of a crime shall be determined based on evidence; no facts may be deemed criminal without evidence.” This clearly reflects the principle of presumption of innocence—if there is insufficient evidence, no crime can be established. Similarly, in civil litigation, evidence gathering is critical. After a lawsuit is filed, a preparatory procedure takes place, during which both the plaintiff and the defendant must gather their own evidence. For example, if you file a civil lawsuit for “violation of spousal rights” or “water leakage and noise in a house,” you must provide your own proof of infidelity or property damage. If the evidence is incomplete, there’s a high chance you'll lose the case, leaving you frustrated and financially burdened.

Therefore, Yitong Investigation Agency believes that everyone should have a basic understanding of evidence collection. Whether it's chat messages, audio recordings, videos, or witness testimony, it’s essential to know whether the evidence is legally admissible.

This highlights the importance of evidence in both criminal and civil cases. That’s why investigation agencies typically use both audio and video equipment during on-site investigations—to capture any ongoing criminal behavior for use in future court proceedings or negotiations. Common scenarios include catching a cheating spouse in the act or conducting covert surveillance and filming.

It’s often said that recordings made without consent are inadmissible and could even constitute a criminal offense for violating privacy—is that really true?

Whether the materials you’ve spent time collecting have probative value is a critical issue. If you go through the trouble of obtaining audio or video recordings, only to find they cannot be used as evidence in court, not only will your efforts be wasted, but your case may also be negatively impacted, potentially resulting in a loss. That’s why investigation agencies are especially cautious about how evidence is obtained and ensure compliance with relevant legal provisions, so that the collected recordings have sufficient evidentiary weight and investigators are protected from potential counterclaims by the opposing party.

When it comes to audio and video recordings collected by individuals, the rules for admissibility as evidence differ significantly between civil and criminal law.

• Criminal Cases
  
  

  When it comes to whether audio recordings are admissible in criminal cases, judicial opinions vary in practice. Some judges believe that as long as the evidence is obtained voluntarily (i.e., the recorded statements were made without coercion or threats), the recording can be accepted. Others argue that the validity of evidence depends on whether the method of obtaining it violates the Criminal Code’s provisions on illegal recording or the Communication Security and Surveillance Act.

  According to the Criminal Code, if someone uses tools or devices without just cause to spy on, eavesdrop on, film, photograph, or record another person’s private activities, speech, conversations, or private body parts, it constitutes the crime of “infringing upon personal privacy.” Moreover, illegally monitoring another person’s communications constitutes “illegal surveillance.” However, the law provides an exemption: if you are one of the parties in the communication, or if you have the consent of the communicating party and the recording is not made for unlawful purposes, it may be legally permissible to record.

  In other words, when collecting evidence, one must be mindful of whether the statements were made under coercion or threat, whether someone else’s communications were secretly recorded, and whether the purpose was legitimate. Otherwise, the hard-earned recordings may not only be inadmissible in court but may also be deemed illegal.

• Civil Cases
  
  

  Compared to criminal cases, civil court judges assess the admissibility of recordings based on principles such as "good faith," "due process," and "the extent to which unlawfully obtained evidence infringes on others’ rights." Simply put, it’s a question of proportionality. For example, if the evidence was collected purely for personal gain, and the method involved large-scale, long-term surveillance or recording of someone’s conversations, the court may determine that there was no legitimate purpose. This would be considered a violation of constitutionally protected rights, rendering the evidence invalid.

Have you ever wondered whether the guesthouse you're staying in is operating legally? How can you gather evidence against illegal accommodations? Is it legal to use audio recordings as evidence?

Some guesthouses operate as illegal short-term rentals rather than being officially licensed under local regulations. These types of accommodations often attract a constant flow of tourists who party late into the night, disturbing the peace of local residents. This has become a recurring issue in many communities. If you encounter problems such as noise or environmental damage in your neighborhood, you can gather evidence through audio and video recordings and report it to the relevant authorities. Offenders can be penalized under the Apartment and Building Management Act, and if the rental is being operated illegally, enforcement actions will also follow.

In addition, many guesthouse operators promote their properties with attractive photos and descriptions, claiming beautiful surroundings, clean rooms, and indoor hot springs. However, upon arrival, guests may find moldy, damp rooms, rundown facilities, and corroded drains. In such cases, we advise guests to take photos to document the situation and compare them with the online advertisements. This can serve as solid evidence of false advertising.

As for the legality of audio and video recordings, let’s return to the case mentioned at the beginning. The woman who came to us wanted to obtain proof of her husband’s infidelity. She had been secretly monitoring his phone conversations over a long period and on a wide scale, even capturing confidential business discussions between her husband and his subordinates. This clearly exceeded the principle of proportionality in civil investigations and risks rendering the evidence inadmissible. Worse, it may also constitute violations of the Criminal Code’s privacy protection laws, such as the crimes of infringing on secrets and illegal surveillance.

Therefore, we strongly recommend that anyone with investigative needs seek professional legal advice before proceeding. While invalid evidence may be a small setback, crossing legal boundaries can lead to serious consequences. Yitong Investigation Agency has professional investigators and legal consultants. If you have any related concerns, feel free to contact us for a free consultation.