salon tango rules
Check out Terence Clarke’s Huffington Post article on the 2012 champs here http://www.huffingtonpost.com/terence-clarke/tango-dance-world-cup_b_1768005.html

J. Ramada Salieri and Yumiko Krupenina won the U.S.A. Championship in the Salon Tango competition, in which improvised tango is the rule
The rules are outlined on the official site:
Salon Tango Evaluation Criteria: Salon/Stage
In this category, couples will compete in groups, dancing three pieces previously selected by the Committee.
1. About the Position of Tango Dance:
a. Once a couple forms a dance frame, the partners shall not separate as long as the music is playing. This means that they cannot break the embrace, which is considered as the Tango dance position.
b. For the position to be considered correct, partners must constantly hold each other by means of the embrace. It is understood that, in certain figures, this may be flexible; but not throughout the entire piece of music.
c. All movements shall be performed within the space allowed by the couple’s embrace.
2. The Judges will give special relevance to the couple’s musicality, elegance and walking style.
3. Within these guidelines, participants may perform any figure commonly used, including barridas (sweeps), sacadas (close to the floor), enrosques (twists), etc.
4. Ganchos (hooks), saltos (jumps), trepadas (climbs) and any other typically stage Tango possibilities are completely excluded.
5. Couples, as in a real dance hall, must constantly move counterclockwise and avoid remaining in the same place.
6. None of the members of the couple may lift his/her legs beyond the line of the knees.