You may have noted that "Dr. Fuchs" is acting quite like an absent-minded professor while trying to cover that up as best as he can. The absent-mindedness, in which he briefly forgets what he's doing or certain little (or not-so-little, such as his vendetta against Edgeworth) details, is one of the consequences of his
experimental trial, which happened during NS 44. A micromachine inside the bullet that was re-implanted back into his shoulder is delivering electrical charges at random to his brain, causing temporary lapses of memory. He's unaware of the electrical impulses per se, and he doesn't know that he's forgotten anything until after the fact, if at all. If he does realize it, he will try to compensate for it as best as he can to save face -- as is typical for him.
Another effect of this micromachine is that very occasionally, he will show signs of having a true "conscience." That is, his line of thinking will shift more towards the genuinely unselfish and have more profound insight as to why his past actions have been wrong. It's a hard concept to explain, but it's sort of like the difference between just intellectually knowing something is wrong, and feeling it deeply. Should this happen, he won't act upon it (except in very minor, inconsequential ways, so he still won't go out of his way to save someone's life during NS out of the kindness of his own heart). Once the moment passes, he will realize that it's Landel's doing, thus strengthening his resolve to bring down the whole damned institute.
The effects are permanent, but they will gradually decrease in severity and frequency over a period of one in-game week, starting on Day Shift 46 and ending on Day Shift 52. (Due to the "real life" event, Day Shift 45 isn't counted in this week, although he will still suffer the effects on that day.)