Sounds like we're quite some way from an 0% failure rate. 11% of a population of murder victims (n=231) had a restraining order in place against their killer at the time of the homicide. Although only a small number of all the restraining orders issued result in homicide, courts in one state found that domestic violence restraining orders were violated about 1/3 of the time, whilers self-reported a total closer to 60%.

https://www.ncbi.nlm.nih.gov/pubmed/18523113

http://extras.denverpost.com/news/violence/viol0912.htm

'too ridiculous to be taken seriously' - I'll put hard data up against epistemological hand-waving any day of the week. I fact-check my claims before I state them publicly.