Mikeirvin & GirlOnFire,
While your point on trafficing is true, GirlOF , I think you are quite naive about what is really going on in this country and across the world concerning pornography. I suspect because of the internet most of the pornography being produced today is by willing couples. I've studied this for many years and come to the conclusion it cannot be all forced upon women. Sad to say our culture (in America especially that repeats the idea the Constitution supports every kind of freedom... good or evil) and across the world is sexually charged. There is a book out called Pornified, I've not read it yet but I have heard the author (Pamela Paul) interviewed many times. One thread in her thought is that our culture is saturated with the mindset that sexual license is good. I mean look at our society today... would you ever have believed someone who forecast that homosexuality would be culturally sanctioned in the future? Not just sanctioned by opinion but laws being written to enforce an attitude that promotes it rather than the other way around!
No, there are women forced into slavery in our modern world, sexualy slavery included, expecially in foreign countries, but also here in America, and I suspect the larger driving force behind porn is not just the complaciency of the American public, but the high participation rate of men AND women willing to broadcast their most private life on video. I also suspect there are many many naive women who allow their "boy friend" to make videos of their sexually intimate relationship, then they break up and that video ends up on the internet. In fact I suspect not even a breakup is needed for a "home made" porn video to make it to public view. Furthermore many women consider it a badge of womanhood that they display themselves fully naked on video and many even engaged in the act. It's the "new sexual freedom" guarded so zealously by the modern feminist movement that has lost it's way abandoning the prolife stance of the original feminists. They are in government and politics on the forefront of the liberal progressive movement that hates anything of traditional or conservative opinion.
All this is beause of the common ideas we hold concerning human sexuality. It is contrary to the Christian mindset that considers all human life sacred. If this is true then the means by which human life comes into our world must also be sacred. Unfortunately this very Catholic idea is not just frowned upon but hated. It is hard for me to find people who support this idea that we cannot interfere with human sexual act. We can treat it when disordered but it is morally wrong to try to change it's nature, of which, is the exact purpose of sterilization and contraception. The almost entirely Catholic idea of Natural Family Planning is spat upon by our culture. I mean by this that few people have heard of it and those who have don't understand the implications of the secular ideas they hold of human sexuality. Most think it is the "rythym method," which is far from the truth.
No, what you two must understand is that the Church Christ initiated teaches us to have both custody of the eyes as well as dress in moderation. Instead we are confronted day after day by a society that teaches men to be voyeurs and women to be exhibitionists. Underneath these innate ideas is the contraception mentality that teaches childern are "unwanted." This is what Fr. Paul Marx claims has driven abortion (and given us the "abortion on demand" Supreme Court decision of Roe vs. Wade in 1973) and as I have studied and walked at abortion clinics I find it to be the root cause behind our sexual miseducation. This problem goes that deep... down to the level of how children are educated in our government run schools. It has to do with a lack of enforcing existing pornography laws, which by the way, even if enforced has become of lesser effect because of video technology and the internet, and the ability it has given the average person to broadcast their behavior and that of others.
In another book by Dr. Judith Reisman on the Kinsey Institute (and I heard her speak at prolife conventions) where she connects pornography with homosexuality. She said Kinsey who drove the sexual movement back when Margaret Sanger was also around, did what he called sexual research, but was actually torture of young children. He claimed from this "research" that at least 10% of the population was homosexually inclined. What most people don't realize, those who have not looked closely at the issue of human sexuality, is that all of the societal sexual ills are connected. Sterilization, contraception, abortion, pornography, prostitution, homosexuality, masturbation, divorce and remarriage, adultery, fornication, embryonic stemcell experimentation, in virtro fertilization, cloning and even other unethical genetic manipulation and experimentation like sex selection, etc... are all related in that they somehow/someway violate the norms due to our human sexual nature. What we Christians fight against is an immense and very fluid understanding of human sexuality that has little to do with what we are, or in other words how God designed us. These mistaken notions do not comply with our nature that is to be human persons and attack what the Church has always taught about the dignity of every human person.
So in brief, to answer your question, Mikeirvin, the average person has never read what Pope Paul VI has written in his encyclical Humanae Vitae (Of Human Life). Even the average Christian has been poorly educated to realize that there are two distinct meanings to human sexuality. Pope Paul calls them the unitive and procreative meanings. These reasons for our sexual nature can be rephrased as love (unity) and life (procreation). They belong in marriage where they can be not only sanctified but protected by a proper understanding of how human sexuality works.
So you must realize that you open a whole can of worms here with your question concerning married couples viewing pornography... or more precisely the sexually intimate acts of another couple. The answer involves what I have touched on here but also questions concerning the morality of oral and anal intercourse within marriage. It also must include how we define marriage, not just as "consenting couples" but as a man and woman who agree with each other that they will obey God's design (His intent and consequent rules) for marriage. I think Pope Pius XI did a masterful job in his encyclical Casti Connubii (On Christian Marriage) where he laid out that it is God who gave us human nature and human sexuality and so it is He who tells us what marriage is and gives it's purpose and limits. So I also suspect that the suggestions given in this thread so far concerning lust are good, but so far only the tip of the iceberg when trying to answer your question.
In fact this whole subject is of such importance and consequence and neglect in our society that it should be a central political issue...unfortunately, sad to say our culture is not ready for it. Most people, even well meaning persons, who honestly search for what it means to be in a good relationship, have little means to gaining an understanding of what are its ingredients. Catholic Church teaching on the subject is so misrepresented as to be an evil in the eyes of our cultural mindset. The secular educational and political institutions as well as the entertainment industry must all be reshaped for the true understanding of human sexuality to be known and shared by each and every person whom God created, in love, too love and be loved. Pornography is contrary to that love inside and outside of marriage because it is based on and promotes a view of human sexuality and freedom that is contrary to our very nature. We are free to do good, never evil, and our nature is not maliable in the way society today claims it is. Our purpose is to get to heaven to be with God for all eternity, and it is also our responsibility to take everyone we know with us. Especially holy matrimony has this responsibility since God put His stamp of approval on it by making it a sacrament which dispenses special graces so that a man and woman can go against all the strange notions of our culture and live according to God's will when it comes to our sexuality.