Slapper creates a rogue PTP network which allows it to communicate with other clients and participate in a distributed DoS network attack. Symantic rates the severity of this worm as being 2 out 5, 5 being the most severe. Klez, for example, was 5. The worm is spreading very slowly, as far as worms go.
In fact, the court ruled that the state had already proved its case and no trial would be necessary; all that needs to be done is to determine the penalty. Heckel tried to take his case to the supreme court, but they refused to hear the case.