Jury of Peers?

So let's start with a quote from Wikipedia:

The definition of obscenity differs from culture to culture, between communities within a single culture, and also between individuals within those communities. Many cultures have produced laws to define what is considered to be obscene, and censorship is often used to try to suppress or control materials that are obscene under these definitions: usually including, but not limited to, pornographic material. As such censorship restricts freedom of expression, crafting a legal definition of obscenity presents a civil liberties issue.

So tell me how a California couple can get prison time for "a felony charge of conspiracy to distribute obscene material through the mail and over the Internet" to Pennsylvania.

First of all, why are Californians being subjected to Pennsylvania law? By that logic, every single person on the internet is committing some crime since some places that read their emails/blogs/posts/etc do not allow free thought (say, China for instance).

Secondly, how can there be a such thing as "federal obscenity statutes" when even according to Wikipedia, the definition of obscene differs between communities or even individuals in a community. I think this is just the type of thing Wikipedia warned of with "civil liberties issue". By this token, I think Oregon should send to prison everyone on the internet that posts a non-liberal comment... anything religious or right-wing should do. Maybe we should start with U.S. Attorney Mary Beth Buchanan, of the Western District of Pennsylvania for violating Oregonian perceptions of decency.