I'm sure someone could add this if anyone would use it. Blackcoin has a BlackHalo also. Basically, this concept only protects against the situation where one party walks away from the contract, which is not as common as you'd think. It cannot prevent against misunderstandings or against fraud, which is far more prevalent, since there are only two parties involved and one can still lie (with no arbiter and no recourse). In the end, it's A's word against B's word.
The Halo's do not really address the most common causes of contract breach. They are slightly better than nothing, maybe half a step beyond the starting line. That limits them to small transactions where parties are comfortable taking on 90+% of the contract risk themselves.