What is FSSP?

What is FSSP? And why are they prohibited from celebrating in some Diocese (at least, that’s what I heard)?

Here is the link to he international headquarters:

fssp.org/en/index.htm

and to the North American headquarters:

fssp.com/main/index.html

and the general info

fssp.com/main/general.html

 **In 1988, Pope John Paul II canonically established the Priestly     Fraternity of St. Peter as a society of apostolic life and approved its constitutions. The     Fraternity was founded in response to the Holy Father's call to ecclesial unity and the     new evangelization. Hence, our name denotes a filial love and loyalty to the Supreme     Pontiff.**

Kewl, most thanks!

DISCLAIMER: The views and opinions expressed in these forums do not necessarily reflect those of Catholic Answers. For official apologetics resources please visit www.catholic.com.