Are Magic The Gathering Proxy cards illegal to print?
Seems that Wizards Of the Coast classifies it as full on illegal unless the card is made by a judge in a tournament when the original card is damaged.


  Policy Regarding Proxies and Counterfeits
  Proxies
  
  Proxies are substitute cards created solely by judges in sanctioned tournaments pursuant to the official tournament rules. These substitutes are allowed when authorized game cards become unplayable during a sanctioned tournament because of damage or excessive wear. Proxies do not include any graphical reproduction of their intended substitutes.
  
  Counterfeits
  
  Counterfeits are copies or reproductions of actual Wizards trading cards, whether or not they are identified as non-genuine. The creation and distribution of counterfeits violate United States and international copyright laws and negatively affects the integrity of Wizards’ trading card games. Counterfeits are strictly prohibited, even for personal, non-commercial use.


http://www.wizards.com/Magic/TCG/Resources.aspx?x=magic/rules/cardpolicy