Only a newly dreamed-up executive oversight board would be able to prevent specific cases of spying - and even then a majority of the nine-strong board would have to object.
Actually, this "oversight board" has no power at all: it can only emit opinions, it has no way to enforce them. It has been included in the law merely for decorum (and also quite probably in order to be able to give a sinecure to a few more friends).
Even worse, in cases of "emergency" (which are nowhere defined in the law) the spooks have complete free rein: they can bypass both the board and the PM office. Sure, the PM office has to validate the case within a few days, but then it's already too late, the spying already took place, the data is collected and safely stored.
Funny side note: today the French culture ministry tweeted about the 66th birthday of Orwell's 1984 first publication, then deleted the tweet a few moments later. Perhaps they feared it would remind the citizens that this law is nothing more than Big Brother watching them?
Anonymous, just because I still can.