What are the advantages and disadvantages of dynamic scoping?

Disadvantages

• Inability to statically check for references to nonlocal variables.
• Dynamics scoping also makes program difficult to read because the calling sequence of subprograms must be known to determine the meaning of references to nonlocal variables. 
• There's no way to protect local variables from being accessed to by subprograms because local variables of subprogram are all visible to all other executing subprograms, regardless of textual proximity.
• Accessing to nonlocal variables in dynamic scoping takes far longer than accesses to nonlocal variables when static scoping is used.

Advantages

• On the other hand, the only advantage of dynamic scoping is writability. It is more convenient and it provides more flexibility than static scoping. For example, in some cases, some parameters passed from one subprogram to another are variables that are defined in the caller. None of these need to be passed in a dynamic scoped language, because they are implicitly visible in the called subprogram.