The FCC (The Federal Communications Commission) does not say what programs cable companies should have in their line up or not, but it can limit the cable companies in what is considered to be decent and indecent.
United States courts have ruled that material, even if indecent, is still protected by the First Amendment (Freedom of Speech) and can't be banned altogether. However, it can be limited to what is shown, when it is shown and how much of it is shown. This basically means if there is a high chance that a child may see something that is inappropriate, then the cable network showing the program must restrict what is considered inappropriate to avoid a child seeing too much.
Therefore, the FCC doesn't censor television shows but it can restrict what is shown and at what times it is shown. Most often if there is something that a child shouldn't be watching, the FCC has stated that it must be shown later on at night when chances are slim that a child will still be up to see it.