Society and policy makers have long struggled with finding effective ways to protect the public from sex offenders. A sex offender is a person who has been convicted of certain sex offense crimes. Examples of sex offenses include:

• Sexual conduct with a minor
• Sexual assault
• Sexual assault of spouse
• Molestation of a child
• Continuous sexual abuse of a child
• Infamous crimes against nature
• Lewd and lascivious acts
• Indecent exposure and public sexual indecency
• Taking a child for the purpose of prostitution
• Sexual exploitation of a minor
• Incest
• Kidnapping, aggravated assault, murder, unlawful imprisonment, and burglary (when the offense includes evidence of sexual motivation)
• Failure to register as a sex offender
• Violation of Sex Offender Registration statutes

Most offenses involving criminal sexual conduct fall within the jurisdiction of state law, but federal law also includes a number of sexual offenses. The offenses are found in Title 18 of the United States Code. Some of the federal offenses specifically apply to sexual offenses committed within the territorial jurisdiction of the United States or in a federal prison. Other crimes involve offenders who cross state or international borders to commit, or in the commission, of a sexual offense. For example, 18 U.S.C. section 2251 makes it illegal to knowingly print, publish, or cause to be made, "any notice or advertisement seeking or offering to receive, exchange, buy, produce, display, distribute, or reproduce any visual depiction involving the use of a minor engaging in sexually explicit conduct. This statute also applies when such person knows that such notice or advertisement will be, or has been, transported in interstate or foreign commerce by any means, including by computer."

Federal sexual offense include:

• Selling or buying of children (Section 2251A(a)(b))
• Certain activities relating to material involving the sexual exploitation of minors, including both distribution and receipt of visual depictions in books, magazines, periodicals, films, and videotapes (Section 2252)
• Certain activities relating to material constituting or containing child pornography (Section 2252A)
• Production of sexually explicit depictions of a minor for importation into the United States (Section 2260)
• Transporting an individual in interstate or foreign commerce with the intent that the individual engage in prostitution or other illegal sexual activity (Section 2421)
• Transportation of minors in interstate or foreign commerce, with intent to engage in criminal sexual activity (Section 2423(a))
• Interstate or foreign travel with intent to engage in a sexual act with a juvenile (Section 2423(b))
• Use of interstate facilities to transmit information about an individual under the age of 16, with "the intent to entice, encourage, offer, or solicit that minor to engage in any sexual activity that can be charged as a criminal offense." (Section 2425)