The lawsuits challenge forces that do not usually have to account for the use of their power.
The number dropped to 3 in 1996 because of a lawsuit challenging the Texas system.
A lawsuit challenging the system is to be heard this winter.
An earlier lawsuit filed by residents also challenged the plan.
Other lawsuits challenged particular answers to questions on the multiple choice test.
Two other lawsuits are challenging the stadium on environmental grounds.
Rather, they intend to file a lawsuit challenging the new system.
US airlines are bringing a lawsuit challenging the legal basis for the plan.
That is a critical factor because it will no doubt give rise to lawsuits challenging the plan.
One risk is that there are several lawsuits challenging how the surcharge will be set.