What demonstrates that the voting rights act of 1965 was successful?

The Voting Rights Act prohibits discrimination on the basis of race or language minority status (i.e., Asian Americans, Native Americans, Alaskan Natives, and Spanish-speakers). Section 2 of the Act applies across the country and bars the use of voting practices or procedures that discriminate against members of such protected classes. For example, Section 2 has been used successfully to attack restrictive voter registration requirements and the locations of polling places at sites inaccessible to minority voters.

it was certainly a debatable decision, mainly because it was based primarily on political - and not on legal or social - views. since the congress at that time was led by members of the republican party, and the territory that the tribes wanted to turn into an exclusively indian state was predominantly democratic, the proposal (as expressed in the constitution) did not succeed, but the constitution itself proved to be of crucial importance in the creation of the state of oklahoma, and, most importantly, it guaranteed the involvement of representatives of the indian tribes in the government of the future joint state.  

as a member of congress, i would have voted to ratify the constitution, or at least to have it tabled. ignoring it was an interested and partial decision.  

to force terrorists groups to stop attacking western targets using massive military force.