Justice as is thought of in the legal profession can always be seen to be done. But then again, from what I have experienced thus far, lawyers are very conditioned in thier beliefs. Thus a lawyers perception of justice is usually not one shared by the general populace, this may be one of the reasons lawyers are surrounded by such stigma. This may then seem to negate any view of justice that the lawyers have, as it is in contrast or contradiction to that of the general non-legal populace.
However, if we were to rethink the idea of legal justice and model it upon the lines drawn out by popular perceptions of it, we could all wave goodbye to the fair trying of someone convicted of a hienous and well covered crime.
So I think justice is almost always done due to a relationship between public perception and legal perception, but when it goes wrong ios usually due to one or the other rejecting the other outright.

Just my thoughts.