The robustness of rights refers to how stringent or lax we should be when interpreting an amendment. Each amendment obviously has limits to how far the rights can extend.
For example, the first amendment allows you to make any type of film you want…except child pornography. It is commonly accepted that child pornography should not be covered by first amendment rights. On the other side of the spectrum, I can’t think of anyone ever suggesting that the government should ban Dora the Explorer from being covered by first amendment rights. In the middle of the spectrum is rife with debate. Right now the court is debating whether to deny first amendment rights to crush films.
This survey deals with the second amendment rights.