Employment of animation artists, writers and technicians go two directions at the bigger studios these days.
Route #1: People are hired "at will", meaning somebody gets employed at the start of a project and laid off at the end, no muss, no fuss and (mostly) no personal service contracts. (This is the road Disney Animation Studios and most television cartoon shops currently travel.)
Route #2: People are employed after signing a Personal Service Contract.
These contracts are either "term" (guaranteeing the employee a defined period of employment, say "June 1, 2008 to May 31, 2009") ...
Or "at will" (meaning no defined period of employment, just the phrase "employed until such time as services are no longer required" embedded somewhere in the document).
Now. Why am I going through this tedious, legalistic crapola? Because, from recent evidence, studios using Personal Service Contracts have undergone a sea change. They are now paying closer attention to which employees are "at will" and which not because of a 2006 California Supreme Court ruling:
... [I]n Dore v. Arnold Worldwide, Inc. ... an employment contract containing an "at will" clause and without a definite term for employment means that either an employer or an employee can terminate that contract without cause and without explanation. The particular contract in issue in this case included a provision that the termination could occur "at any time" ...
What we were seeing a year and a half back were PSCs (Personal Service Contracts) that had mushy language about artists being employed for "run of picture", but without any guarantee of long-term employment.
The animation guild kept saying: "Hey, this is an at will contract, you can lay your employee off when you want, so your employee can leave when she wants."
But some studios kept telling us: "Oh no! These are term deals. These folks have to stay until the end of their assignment. Forget that there are no hard end dates."
Now, however, "run of picture" PSCs are giving way to contracts that are actual term deals ("May 1, 2008 to May 2, 2009").
It took the California Supreme Court to do this. When it was just little us, some 'toon factories maintained that "at will" agreements were really "term." Interesting what a few well-placed judges can do.