From a legal perspective, it is useful to separate the issues of online therapy/counseling from interstate practice. Each state regulates practice within its own borders, so if counseling or therapy is regulated by a state, and both the counselor/therapist and the client are in the same state, that state's laws and regulations will apply.

However, when the two parties are in different states, the practice may be covered under the more restrictive of the two sets of laws. If the client's state prohibits practitioners in other states--or those not licensed in by that state--from practicing counseling or psychotherapy, the service provider may be practicing illegally in one or both states.

The issues are similar to those affecting the practice of telemedicine. Without arguing for or against, the fact of the matter is that professional licensure (with a few exceptions like nuclear power plant engineers) has always been considered a state function, and until all states (and other jurisdictions like DC) come up with reciprocal licensing agreements or some other accommodation, your advice--in effect, caveat emptor--should apply. And therapist/counselors acting in good faith should also be confirm where their clients are and whether they may be violating the law in the state they are in OR the state their client is in at the time. A little legwork up front can save a lot of angst later on for both parties.