#2 is correct. The key is that it says "the new laws ARE supposed to prevent crime." "Are" means right now, in the present. The laws are new. Today, people hope they will prevent crime, but we don't know yet if they will. If the sentence had said "the new laws WERE supposed to prevent crime," that tells us that in the past, when they were made, people hoped they would prevent crime. "The new laws were supposed to prevent crime" doesn't actually tell us whether they worked or not. Either of these two statements would be possible: "The new laws were supposed to prevent crime, but they failed completely." "The new laws were supposed to present crime, and they did. However, they created other problems."

The new laws are supposed to prevent crime - closest meaning is 2. The new laws should prevent crime but you will have to wait until the future to find out. another example: My new phone is supposed to be waterproof, but I won't find out until it falls into the water.

The new laws are supposed to prevent crime. 这个新法律被认为是预防犯罪的。 1. The new laws should have been to prevent crime but they didn't. 这个新法律本应该预防犯罪，但是没有起作用。 2. The new laws are looked to prevent crime, I don't know if it will work down the road. 这条新法律被指望着预防犯罪，我不知道它是否会沿着这个方向去进行（展开）。