The thing to remember if you are in the USA is that treaties PREVAIL over domestic law. Thus, all those prior court decisions in favour of the consumers no longer apply. A treaty can thus be used as a way for the government and its business partners to circumvent precedents from court cases.
Sure, people talk about fair use, but liberal usage came about as due to a precedent from a court case. After ACTA is ratified, that liberal fair use precedent no longer is valid. The right of the consumer to have a backup copy will also be lost as that was also a precedent created from a court case. Limited forms of reverse engineering may also disappear as they were set by court precedent. Thus, things like the Ragnarok Online MMORPG eAthena emulator would be illegal (it currently is legal) if Gravity reported it.
ACTA uses the “imminent” concept which isn’t really a thought crime. It means that sites creating imminent situations of copyright infringement would also be illegal. Thus torrent search sites (which don’t even host a tracker) would also be illegal as they foster _imminent_ conditions leading to copyright infringment.