Many jurisdictions require PIs to be licensed, and they may or may not carry firearms depending on local laws. Some are ex-police officers, although many are not. They are expected to keep detailed notes and to be prepared to testify in court regarding any of their observations on behalf of their clients. Great care is required to remain within the scope of the law, otherwise the investigator may face criminal charges. Irregular hours may also be required when performing surveillance work.

PIs also engage in a large variety of work that is not usually associated with the industry in the mind of the public. For example, many PIs are involved in process serving, the personal delivery of summons, subpoenas and other legal documents to parties in a legal case. The tracing of absconding debtors can also form a large part of a PI's work load. Many agencies specialize in a particular field of expertise. For example, some PI agencies deal only in tracing. Others may specialize in technical surveillance countermeasures (TSCM), or Electronic Counter Measures (ECM), which is the locating and dealing with unwanted forms of electronic surveillance (for example, a bugged boardroom for industrial espionage purposes). Other PIs, also known as Corporate Investigators, specialise in corporate matters, including anti-fraud work, the protection of intellectual property and trade secrets, anti-piracy, copyright infringement investigations, due diligence investigations and computer forensics work.

Increasingly, modern PIs prefer to be known as "professional investigators" or Licensed Private Investigators(LPI's) rather than "private investigators" or "private detectives". This is a response to the image that is sometimes attributed to the profession and an effort to establish and demonstrate the industry to be a proper and respectable profession.

Global focus

In some countries private investigations are illegal, but they thrive in other countries, including: Australia, Canada, Austria, Japan, Mexico, the Netherlands, the United Kingdom, the United States, South Africa, Spain, and Turkey. In South Africa, private investigators are in very high demand due to poor police work and high crime rates. Other countries throughout the world have private investigators, but many of their duties are restricted. In South Korea, for example, surveillance is allowed only in insurance fraud situations. Some countries in the world require licensing of private detectives, but most do not.

Working conditions

Private detectives and investigators often work irregular hours because of the need to conduct surveillance and contact people who are not available during normal working hours. Early morning, evening, weekend, and holiday work is common.