Consider, for a moment, that you suspect your spouse is cheating or one of your mobile employees are engaged in some kind of theft (even if just "stealing company time"). So you install a GPS tracking device. But what does the GPS tracking provide, other than information about a vehicle's whereabouts? This could be troubling if your spouse or employee is one location when he or she claims to be in another. But this certainly does not prove anything other than a lie, and maybe not even a bold one.
Let's take the example of the cheating spouse. At conferences, investigators often share stories and a common one usually includes observing a suspected cheating spouse do peculiar, not necessarily damning, things. For example, instead of infidelity, sometimes spouses have "personal side activities" that they simply want to claim as their own. From the field, this has involved everything from taking classes at a community college, writing a novel in a coffee shop, shopping, and volunteering to be a conversation partner with a lonely senior citizen. A GPS unit alone leaves it up to the imagination about what is really going on. Sure, your partner may not be truthful, but when you reveal you've been covertly tracking his or her movements with a GPS device, this is likely to cause more strain to the relationship than his or her secret volunteer work. A private investigator can confirm, by observation, what is really going on before you damage your relationship. Oh, and the most important part: electronic tracker laws vary by state and are changing rapidly as courts resolve civil suits. In short, what you are doing could be illegal. If it is legal, but you are hot tempered, remember that a professional investigator acts as a buffer. If you get angry and confront your spouse "in the act," even if it really is cheating, then you could find yourself dealing with assault charges. A private investigator does not immediately reveal details, giving you a chance to "cool down."
Today, inexpensive technology has made it possible for lay people to do all kinds of investigations one limited to the private detective. But the laws are often unclear about the boundaries between the legal and illegal. It is for this reason that Harvey Silvergate claims we commit at least three felonies a day (see article). In recent court cases, people have been arrested and charged for felony wiretap for doing very basic things, such as recording with sound, tracking a person's computer activities [another article], and pretexting (pretending to be someone else to obtain information). Professional investigators take continuing education courses to say abreast of the shifting boundaries. Importantly, they assume the risks of the investigation rather than the client.
The best way to protect yourself legally and to insure you are "getting the facts straight" is through good ol'- fashioned detective work performed by a qualified, insured, and licensed professional investigator. As the saying goes, you get what you pay for and, in today's world, one could rephrase this saying: you may pay (in jail or by ruining your relationship) for what you don't pay for.