Since 1995 a certain number of Member States (Austria, Belgium, Denmark, Finland, Germany, Luxembourg and Sweden) have signed open skies agreements with the United States. Already in 1994, the Commission reacted to the US open skies initiative which would cause discrimination within the internal aviation market, and made it clear in a letter to the Member States that the conclusion of such bilateral agreements would affect the internal aviation market. In 1995 and 1996, the Commission sent therefore, as stage one in the legal procedure, letters of formal notice to the Member States concerned informing them that the individual open skies agreements negotiated or concluded with the United States constituted an infringement of Community law.
La Commission a ainsi clairement expliqué, dans une lettre aux Etats membres, que la conclusion de ces accords bilatéraux affecterait le bon fonctionnement du marché intérieur de l'aviation. En 1995 et 1996, la Commission européenne a donc envoyé, en tant que première étape de la procédure juridique, des lettres de mise en demeure aux Etats membres concernés les informant que les accords individuels "ciels ouverts" négociés ou conclus avec les Etats-Unis constituaient une violation du droit communautaire.