I chose Chandler rather than Hammett because it is the Chandler formula (particularly the first-person narration and snappy dialogue) that became the template for Ross MacDonald, Robert B. Parker, and others.

There are cultural as well as a legal differences between the literary (particularly the genre-literary) and "media" realms. Nobody does more than raise an eyebrow at even the most me-too copycat book that cops some likely component of a successful writer's formula--I've seen quite direct imitations of Dick Francis, Patrick O'Brian (originally commissioned to imitate Forester), John D. MacDonald and Carl Hiaasen (different flavors of Florida crime novels), and so on. Not only is there usually not enough money in the book biz to justify the cost of going to trial, but literary plagiarism is narrowly enough defined that most of the cases I know if just can't be sustained. (Some looney is always claiming that J. K. Rowling ripped off his idea for a story set in a school for magicians, as though the idea or plot skeleton can be owned.)

Hollywood, on the other hand, deploys legions of lawyers and agents to protect quite large investments (and to avoid uncovering any real thefts that do take place). Scripts can be registered, and there are protocols in which various people refuse to even look at a script or proposal so they can't be accused of stealing any ideas.

Ellison characterizes Cameron as saying that he "ripped off" central ideas for The Terminator--but that doesn't mean that Cameron actually used that language or that what Cameron took from Ellison's work would be considered copyright-protected, and copyright violation would be the only basis for litigation. For example, the very first thing I thought when I heard about Avatar was that one of its main motifs was lifted directly from Anderson's "Call Me Joe." But I don't think that re-using that kind of story element ("there's this crippled guy and he. . .") constitutes plagiarism. What I do see in Cameron is what E A Blair describes in his post: "a habit of very consciously and methodically identifying the most popular elements of the most popular stories." That's standard Hollywood "creativity"--look at the opening of Altman's The Player for a nice satirical depiction of the Hollywood story-pitch session--"It's kind of like The Gods Must Be Crazy except the Coke bottle is a television actress." "It's Out of Africa meets Pretty Woman." In a world like that, notions of creativity get, um, transvalued.