Pensieve memories
(Anonymous)
"Pensieve memories cannot be tampered with"
This isn't quite correct. Pensieve memories can be tampered with, but only someone *very* skilful with mind magics can do so convincingly. The one example we see in canon (Slughorn's) has the grafted false memories appear as a thick white fog overlaying the scene. Clearly, Slughorn was not skilled enough with mind magics, despite being enough of an Occlumens to keep his secret from Dumbledore; Snape OTOH probably *was*. Which is all the more reason for the Wizengamot to dismiss his testimony, however obtained.
duj
This isn't quite correct. Pensieve memories can be tampered with, but only someone *very* skilful with mind magics can do so convincingly. The one example we see in canon (Slughorn's) has the grafted false memories appear as a thick white fog overlaying the scene. Clearly, Slughorn was not skilled enough with mind magics, despite being enough of an Occlumens to keep his secret from Dumbledore; Snape OTOH probably *was*. Which is all the more reason for the Wizengamot to dismiss his testimony, however obtained.
duj