'Hossenshiki' (法戦式) literally means "Dharma Combat Ceremony," although we prefer to call it "Dharma Inquiry." In this case, "Dharma" means the Teachings expressed in old Zen Koans. In the "Dharma Combat," the Shuso is seen to take away the "Shippei" (竹箆), a kind of baton carried by a Zen teacher, and the Shuso temporarily assumes the role of teacher. The Shuso is presented a traditional Koan case, and is bombarded with some questions about it. The Shuso responds with expressions meant to illuminate the truth of the Koan. The scene within the ceremony is meant to recreate the scene in many of the old Koan stories themselves in which a student spontaneously and unhesitatingly expresses the Wisdom and Compassion of the Koan with words and poetry coming naturally from the monk's heart in response to challenges from his teacher or another monk. Sometimes the monk might respond with some seemingly mysterious words, somehow seeking to express emptiness and transcendence and immanence, or a poem, or a shout or by drawing a circle in the air. I assure you that this is not done without meaning behind it (at least, it should not be so).
Except, that is not actually how the Hossenshiki is performed in Japan.
In fact, in Japan, the Soto Zen version is anything but spontaneous. In reality, it is totally pre-scripted and well rehearsed for days, a fact due in part to the ceremony being conducted in an antiquated form of medieval Japanese language that even modern Japanese cannot well understand. The monk's questions and answers are all predetermined and memorized. In that way, the ceremony is more like a piece of theatre than an actual combat. However, that is not seen as a bad thing because, in many aspects of Zen training in Japan, it is believed that by assuming a role ... even if scripted ... one actually can pour oneself into the role and become the role (something like saying that, if an actor plays Hamlet with enough sincerity, the actor can actually come to embody Hamlet. In this case, by acting and speaking the words of a Buddha or Zen Master, one can imbibe their spirit.) The Japanese ceremony is generally very serious and stern. The intricate moves of the ceremony, and the precision, mean that the steps must be mastered much as a classical ballet. However, as in dancing an actual ballet, the dancer can literally pour herself into the dance and become the dance.
But our Treeleaf Hossenshiki is a bit different from all that .. and just a bit different in other ways too!
First, portions of our ceremony try to actually bring back some spontaneity to the Q&A, with the participants expected to speak from the heart. (They were informed of the Koan in advance, and the first question, but not the rest after that. The rest was a surprise.) We are not alone in this, as many other Soto Zen Sangha in the west are also trying to have a bit more spontaneity too. In order to do so, we also are willing to walk the fine line of being serious yet light hearted, stern yet smiling or laughing when the time is right. That is actually a good thing because the Koans themselves, when we examine them, are also typically combinations of serious teaching and a good bit of jesting and humor mixed in.