The word "tenuous" is an apt choice to describe the civilization of the island. Even before the complete collapse at the novel's end, there are a few significant challenges to and failures of the rules set up to maintain order on the island.

One of the first rules to be flouted is about the location where the boys relieve themselves. The agreement is that they will use a rocky area so as not to contaminate water and food sources. Though this rule is essential for the common good, some lack the discipline to follow through and demonstrate no shame for their selfish and thoughtless actions that imperil everyone.

The rule about keeping the signal fire going is eventually broken. Jack is the culprit, and his actions constitute a major setback that angers Ralph and frightens Simon when he realizes that the growing resentment Ralph and Jack have for one another is a threat to all.

The rule of having to have the conch in hand to address the group in meetings falls by the wayside as the boys talk over one another. When the conch is broken at the same moment Piggy is killed, their tenuous civilization is symbolically and literally shattered.

Ralph establishes some fairly simple rules for the boys at the beginning of their adventure on the island. 

1. Use the conch in assembly meetings.  Wait for your turn to talk.  Interrupting of the person holding the conch is not allowed.
2. Bring water from the stream and store it in coconut shells under leaves.
3. Keep the fire signal on the mountain going at all times.
4. Use the rocks for lavatory.  Using the bathroom in the fruit trees area is not allowed.

Ralph's rules do not last very long, mostly because Ralph never implements some sort of system of discipline to keep the boys in check.  Ralph's frustrations continue to build almost to a breaking point when he calls the assembly in chapter five after Jack's hunters let the fire go out when a ship passes by.  Ralph vents to the tribe:

"We have lots of assemblies. Everybody enjoys speaking and being together.  We decide things.  But they don't get done" (79).

Ralph's burgeoning leadership over his fledgling civilization is ineffective, because he lacks the authority to enforce the simplest of rules.  The boy's attempt at civilization on the island ultimately fails due to their lack of consistency in maintaining the law and order of the island.