Minnesota has a law which forbids massage therapists from having sex with their clients for two years.  A therapist who violates the law can have his/her license revoked, and be fined.

The problem with the law (aside from the fact that it is a victimless crime) is that it makes no exception for marriage. 

That can cause a problem.  Just ask this lady:

LaRae Lundeen Fjellman likes to think her massage and alternative health business in Lindstrom has a small-town touch. She knows most of her clients personally and often gives them presents, such as flowers or banana bread, on special occasions.

But when she got too close to one of them and fell for former client Kirk Fjellman, who was divorcing his wife, she was surprised to learn that Minnesota bans massage therapists from having sexual relations with former clients for two years.

Kirk says his ex-wife reported LaRae to state officials in 2004. Now, the state is seeking to fine and possibly prohibit LaRae Fjellman from practicing in Minnesota for having sex with someone who has become her husband.

"There’s no harm, no victim," Kirk Fjellman said. "What’s this about?"

Obviously, the law is unconstitutional as applied to Ms. Fjellman.  There is no way that a state can penalize an individual for having sex with their own spouse.

UPDATE:  Yup, North Carolina has similar laws, although not as strict:

.0508 SEXUAL ACTIVITY DEFINED

For the purposes of this Chapter, "sexual activity" shall mean any direct or indirect physical contact, or verbal communication, by any person or between persons which is intended to erotically stimulate either person, or which is likely to cause such stimulation and includes sexual intercourse, fellatio, cunnilingus, masturbation or anal intercourse. As used herein, masturbation means the manipulation of any body tissue with the intent to cause sexual arousal. Sexual activity can involve the use of any device or object and is not dependent on whether penetration, orgasm or ejaculation has occurred.

.0509 SEXUAL ACTIVITY PROHIBITED

To preserve the safety and integrity of the therapeutic relationship, the following requirements shall apply during the period from the beginning of the client/therapist relationship, and continue for six months after the termination of such relationship. Licensees shall:

(1)    not engage in sexual activity, as defined in Rule .0508, between the licensee and the client, whether such activity is consensual or otherwise;

(2)    not engage in or permit any person or persons to engage in sexual activity with a client in a location where the practice of massage and bodywork therapy is conducted;

(3)    not use such location to make arrangements to engage in sexual activity with a client in any other place; and

(4)    define the boundaries of the professional relationship in the event that the client initiates or asks the licensee to engage in sexual activity.