Well LizM, The FCRA (Fair Credit Reporting Act) is the law that dictates what may stay on a credit report for what length of time, it also states that items have to be reported accurately as well as some other things (it's about 80 pages long, if you want to read through it there is a link to it in my signature) it also provides civil penalties for violations ($1,000 per violation or 1% of the companies net worth, whichever is lesser)
The statutes of limitations (which you can find a guide to SOL by state in my signature) provides the maximum number of years that can pass from the date of last activity on a account in which the creditor may file suit.
If you have any further question feel free to ask.