"Obscene, pornographic" scientific legal definition of the world there is no uniform understanding.

In American is also a Public opinions are divergent. proposition. But there are also relatively authoritative, one of the most famous definition which is a social scientist Berhard and Crew Hallson in their paper "pornography and the law".

They think, pornography (obscene) is the main purpose of erotic response.

They cited several major characteristics of pornography, including too prominent figures of the physiological response, distortion prominent sex or forbidden form, highlight the sexual abuse and passive obedience, the expression of non truth and sexual behavior and sexual ability. Anthropologist Margaret Meade put pornography is defined as:"From another love or select the object exists, it is enough to cause the text, or the behavior of lust."

America has the tradition of case law countries, most of which is the case law legislation sanctions obscenity, pornography, namely through the trial of the case and the judicial criterion. Notably, the judicial standards is not immutable and frozen American sanctions pornographic articles, but there is a long historical process. Can be roughly divided into the following three stages:

First, "Hiker forest criterion" stage

In 1873, when the Supreme Court was asked to be the legal meaning postal act on pornography, obscene to explain, the Supreme Court was hastily borrowed from the British "Hiker forest criterion".

In this case the guidelines announced:If a work may lead to dangerous reader vice and corruption, it is obscene.USA court in the application of this rule and believe: as long as one part of a book, play, magazine or other work is obscene, then the whole work is obscene.

The judicial principle is extremely heavy, is widely used for about seventy-five years, it makes the obscenity, pornography trial quite easy in twentieth Century twenty, thirty, forty time, judicial success makes official inspectors in the removal of "obscene" and "obscene" side aggressive. So it was a lot of objection. In 1957, the Supreme Court announced America "Hiker forest criterion" unconstitutional, because it only adults are allowed to read the only suitable for children. The end of the first phase of the announced.

Second, "Ruth -- May Morris criterion" stage

In 1957, is a milepost meaning "Ruth to American" case. Roth for selling "objectionable material", by the local court under federal law on obscenity conviction, the court of appeal also confirmed the indictment. But Ruth appeal, to the Supreme Court on the demolition.

The Supreme Court by a majority of votes in five than four support for his decision. Nine years later USA about obscenity trial standard of the main designers breland judges to verify the pornographic, obscene remarks provided a new criterion:If one works for ordinary people, according to contemporary social standard, its theme to lecherous interest from on the whole, it was obscene.

  "Ruth -- May Morris criterion" has continued, until now still effective.