how csi and ncsi gets written:

executive producer at so and so studio:   ok, our latest batch of writers has died, get me toxicology unit at the hospital

tu: toxicology unit

ep: hi, i need about 10 guys that have a chronic life-long addiction to sniffing white-out.....

tu: ok i have 10 guys in here that fit that description, except they've only been using it every day for the past 5 years

ep: holding the phone down and talking to his assistant, we're screwed, our ratings will plummet