This page is a collection of ideas on how to prevent a potentially abducting parent from boarding an airline with your child. Eventually, this page will probably be divided into ideas "if you have a court order against travel" and "without court order against travel".

Some airlines have internal policies requiring notarized letters.  For example, Continental says the following on its website. (cached copy)

Minors under 18 years of age traveling to Mexico, Brazil and Chile: Notarized letter of consent that has a valid period of 30 days and is good for a single entry.

1. •If traveling unaccompanied: A notarized letter of permission (originals only) signed by both parents and an individual passport.
   

2. •If traveling with only one parent: A notarized letter of permission (originals only) signed by the other parent.
   

3. •In case of deceased or divorced parents: Legal proof must be submitted to accept only one parent's signature on the notarized letter of permission in order to establish that signing parent has legal custody of the minor.
   

This information came to light because of the article referenced below entitled "Continental Airlines Sued for Negligence by Father of Kidnapped
Three-Year-Old Child Illegally Taken by Plane to Mexico by Ex-Wife".  Unfortunately the same policies do not apply to Japan.  But they raise the following points that you could follow up on:

1. •Why isn't Japan on Continental's list?
   

2. •How could we get Japan on Continental's list?
   

3. •Do other airlines have similar rules? If not, can we encourage such?
   

4. •Barring implementation of exit controls, how about a law requiring the same requirements from airlines?
   

You may also be able to bring up this lawsuit to show that airlines may have some liability issues if they do not prevent such abductions.  Perhaps they would have some liability even if they did not have such policies but you notified them of a court order. Check with your lawyer!

Looks like Delta has a similar policy on their website (cached) that is not restricted to any specific countries.  Perhaps other airlines do also.

International Travel With Minors (including Canada & Mexico)
Due to international concern over child abduction, many governments have initiated additional requirements at arrival and departure points when children under 18 years old are not traveling with both parents. Many countries require documentary evidence of the adults' relationship and permission of the parent(s) or legal guardian before they will allow the child to cross the border. Single parents, grandparents or guardians traveling with children often need proof of custody or notarized letters from the other parent authorizing travel. These requirements are in addition to passport or proof of citizenship requirements.

1. •Minor traveling with one parent: If a minor child is traveling with only one parent, the absent parent is expected to provide notarized consent. If only one parent has legal custody, that parent should be prepared to provide a court order of child custody to airlines and international authorities.
   

2. •Minor traveling alone: If a minor child is traveling alone or in someone else's company, both parents (or the sole, documented custodial parent) must provide notarized consent.
   

3. •Minor with a different last name: If a child traveling has a different last name from the mother and/or father, the parents should be prepared to provide evidence to airlines and official authorities, such as a birth certificate or adoption decree, to prove that they are the parents.
   

4. •Minor has one deceased parent: If one parent is deceased, a death certificate is required.
   

5. •Minor has one parent: If the birth certificate shows that the minor only has one parent, it will be sufficient to hold only a notarized copy of the birth certificate.
   

According to Jeremy Morely,  In 2005, a Connecticut jury returned a $27 million verdict against a charter airline company in favor of a mother for negligently failing to maintain adequate safeguards against abductions when it accepted $160,000 to fly a father and his three children to Egypt and then to Cuba.

Essays

1. •How to notify airports and airlines about court orders preventing travel.  (It can and has been done.)
   

Articles

1. •Continental Airlines Sued for Negligence by Father of Kidnapped Three-Year-Old Child Illegally Taken by Plane to Mexico by Ex-Wife; January 29, 2007. Airlines can be sued for negligence in parental abductions, especially if they have a clear policy in place requiring permission from both parents, like Continental did.
   

2. •LOS ANGELES -- A judge properly ruled that an airline does not have liability after a mother flew her daughter to Japan without the permission of the child's father, an attorney for All Nippon Airways said Thursday.
   

3. •A US man has sued Japan Airlines, claiming it wrongfully helped his Japanese ex-wife leave the United States with their son, despite court orders that the child remain in California.