Another interesting 2001 article from the SearchEnglish site (aren’t there any more recent articles there?). Isamu Murakami, an MA Student at the University of Durham (or he was; presumably he’s finished now!) writes: HLT Magazine (November 2001) – Major Article 3:

Since I work as a non-native teacher of English in Japan, I am sometimes asked, “How much of the time do you speak English in the classroom?” or “How often do you speak Japanese in the classroom?” When I say, in answer to these questions, “I frequently use Japanese in the class room”, the responses that they give tend to be “You should try harder”, or even “Oh, no!” Also, I have heard many times language teachers in the classroom saying to the students, “Don’t speak Japanese. Speak English” or, “Japanese is not allowed in this room.” It appears that the underlying assumption behind them is ‘the less L1, the better’. I am strongly against this notion….
I would like to argue that better language learning in the EFL context can be and should be promoted by ‘bridging’ the gap between their L1 and L2, deliberately using students’ L1 as a positive resource….
Bridging is not the way to go back to traditional Grammar-Translation Method. Use of native language should not be an excuse for not using much target language in the classroom. Bridging is rather the way towards more ‘humanistic’ language teaching, which respects learners’ mother tongue and their background culture. The ultimate goal of this approach will not to produce many ‘fake native speakers’, but to promote learners’ ability to drive the target language on the basis of their L1 identity. The skill that students in the EFL context should develop is the ability to use the target language with their L1, not without it.