"spirit and the letter (of the law)" is a common phrase in English. For the next part IANAL.

It appears in the US that generally the letter of the law matters more in legal proceedings than the spirit of what was written. Though there is sometimes debate (especially around the constitution) as to what the words meant at the time the law was written which give a little legal freeway to the spirit. From what I have seen though these cases generally deal more with rights/civil liberties than laws which affect corporations/tax codes/processes/etc. There is greater freedom to interpret the spirit of the law in criminal cases (e.g. jury nullification).