I don't want to steal Jon Sourbeer's thunder, but let me offer a more precise answer.
Both Jeff and Art are correct, but they haven't answered the intent (as I read it) of Marshall's question.
In short, TLCA insurance is a benefit, not a requirement. Just like free advertising in Toyota Trails, you don't have to advertise, but it's available to you if you want it and your event is blessed by the BOD.
Insurance is Timm Buchanan (EVP) and he can provide a copy of TLCA's current policy. Both Erik Christiansen and Jennifer Lorincz have multiple years experience in the EVP role and I consider their opinions as expert.
Marshall's post #10 begins the inevitable "what if" dialogue. I am not an attorney and I don't play one on TV. But, I have been sued in civil court. If someone gets hurt at an event and they decide to sue, then their attorney will list the off-road park, the host club, TLCA, each officer of both the host club and TLCA, as well as anyone involved in the incident. This way the attorney has access to the greatest number of "pockets." The off-road park and TLCA require each participant to sign a waiver absolving the park and TLCA (and the host club) from liability. Cool, except the waiver can be thrown out if the attorney can show the park or TLCA is guilty of negligence. There is no magic document to prevent lawsuits or guarantee anything.
To my knowledge, no one has ever sued an event or TLCA. That's the reason we still have a policy. I went to the BOD during my tenure and changed the bylaws to clearly place safety concerns with the host club. At the time, TLCA had money and yet TLCA had no direct oversight of event safety.
Thanks for the bandwidth. TLCA insurance is cheap and gives chapter officers some cover. Most clubs run on a shoestring, TLCA is living "hand to mouth", and anyone wanting to sue you is going to need strong evidence of willful neglect. If any host club fails to act responsibly, parks will turn them away and their own members will leave.
Hope that helps,
Happy Trails! N