NEW YORK - What's scary, funny and boring at the same time? It could be a bad horror movie. Or it could be the fine print on your Internet service provider's contract.

Those documents you agree to — usually without reading — ostensibly allow your ISP to watch how you use the Internet, read your e-mail or keep you from visiting sites it deems inappropriate. Some reserve the right to block traffic and, for any reason, cut off a service that many users now find essential.

The Associated Press reviewed the "Acceptable Use Policies" and "Terms of Service" of the nation's 10 largest ISPs — in all, 117 pages of contracts that leave few rights for subscribers.

"The network is asserting almost complete control of the users' ability to use their network as a gateway to the Internet," said Marvin Ammori, general counsel of Free Press, a Washington-based consumer advocacy group. "They become gatekeepers rather than gateways."

But the provisions are rarely enforced, except against obvious miscreants like spammers. Consumer outrage would have been the likely result if AT&T Inc. took advantage of its stated right to block any activity that causes the company "to be viewed unfavorably by others."

Jonathan Zittrain, professor of Internet governance and regulation at Oxford University, said this clause was a "piece of boilerplate that is passed around the corporate lawyers like a Christmas fruitcake.

"The idea that they would ever invoke it and point to it is nuts, especially since their terms of service already say they can cut you off for any reason and give you a refund for the balance of the month," Zittrain said.

AT&T removed the "unfavorably by others" wording in February after The Associated Press asked about the reason behind it. Subscribers, however, wouldn't know that it was gone unless they checked the contract word for word: The document still said it was last updated Oct. 8, 2007.

Most companies reserve the right to change the contracts at any time, without any notice except an update on the Web site. Verizon used to say it would notify subscribers of changes by e-mail, but the current contract just leaves that as an option for the company.

This sort of contract, where the subscriber is considered to agree by signing up for service rather than by active negotiation, is given extra scrutiny by courts, Zittrain said. Any wiggle room or ambiguity is usually resolved in favor of the consumer rather than the company.

Yet the main purpose of ISP contracts isn't to circumscribe the service for all subscribers, but rather to provide legal cover for the company if it cuts off a user who's abusing the system.

"Without the safeguards offered in these policies, customers could suffer from degradation of service and be exposed to a broad variety of malware threats," said David Deliman, spokesman at Cox Communications.

The language does matter: In a case involving a student accused of hacking, a federal appeals court held last year that subscribers should have a lower expectation of privacy if their service provider has a stated policy of monitoring traffic.

But these broadly written contracts still don't provide all the legal cover ISPs want. Comcast Corp. is being investigated by the Federal Communications Commission for interfering with file sharing by its subscribers. The company has pointed to its Acceptable Use Policy, which said, in general terms, that the company had the right to manage traffic. Since the investigation began, it has updated the policy to describe its practices in greater detail, and recently said it would stop targeting file-sharing once it puts a new traffic-management system in place late this year.

The Comcast case is a rare example of the government getting into the nitty-gritty of one of these contracts.

"There really should be an onus on the regulators to see this kind of thing is done correctly," said Bob Williams, who deals with telecom and media issues at Consumers Union.

If there were more competition, market forces might straighten out the contracts, he said. But most Americans have only two choices for broadband: the cable company or the phone company.

Williams himself knows that it's tough to pay attention to the contracts. He recently had Verizon Communications Inc.'s FiOS broadband and TV service installed in his home. Only after the installation was completed did he get the contract in the mail.

He could have read some of the terms earlier, when placing the order online, but he just clicked the "Accept" button.

"I'm a hard-nosed consumer advocate type ... I really should have examined it better than I did," he said. But, he added, he acted like most consumers, because of the lack of alternatives. "You click the 'Accept' button because it's not like you're going somewhere else."

Other common clauses of ISP contracts:

ISPs can read your e-mail Practically all ISPs reserve the right to read your e-mails and look at the sites you visit, without a wiretap order. This reflects the open nature of the Internet _ for privacy purposes, e-mails are more like postcards than letters. It's also prompted by the ISPs' need to identify and stop subscribers who use their connections to send spam e-mails.

Some ISPs, like AT&T Inc., make clear that they do not read their subscriber's traffic as a matter of course, but also that they need little or no excuse to begin doing so. Cablevision, a cable operator in the Northeast, says one of the reasons it might look at what a customer is doing online would be to help operate its service properly.

The federal Electronic Communications Privacy Act protects e-mail and other Internet communications from eavesdropping, but several of its provisions can be waived by agreements between the ISP and the subscriber. Also, the law is mainly aimed at making it difficult for the government, not companies, to snoop.

Wiretapping laws may also apply, but the situation is unclear. A federal appeals court panel in 2004 dismissed charges against a company that provided e-mail services for booksellers and snooped on their Amazon.com order confirmations. The charges of illegal wiretapping were reinstated by the full appeals court the next year, but the case hasn't been tried.

ISPs can block you from Web sites Or at least they would like to think so. In a clause typical of ISPs, Comcast reserves the right to block or remove traffic it deems "inappropriate, regardless of whether this material or its dissemination is unlawful."

The ISP sees itself as the sole judge of whether something is appropriate. Broad enforcement of this kind of clause for business purposes other than protecting users is likely to draw attention from regulators like the FCC, as is happening in the Comcast file-sharing case.

ISPs can shut you down for using the connection too much For cable ISPs, up to 500 households may be sharing the capacity on a single line, and a few traffic hogs can slow the whole neighborhood down. But rather than saying publicly how much traffic is too much, some cable companies keep their caps secret, and simply warn offenders individually. If that doesn't work, they're kicked off.

It's difficult to reach these secret bandwidth caps unless users are downloading large amounts of high-quality video from the Internet, but the advent of high-definition Internet video set-top boxes like the Apple TV and the Vudu could make it more common.

Oddly, some ISPs, like Cox, say it's the responsibility of subscribers to ensure that they don't hog the traffic of other subscribers, a determination that's impossible for a home broadband user. Cox, however, does make the monthly download and upload limits public on its Web site.

Time Warner Cable Inc. has said it will test putting public caps on how much new subscribers in Beaumont, Texas, can download per month, and charge them more if they go over.

Digital subscriber line providers like AT&T and Verizon aren't as concerned about bandwidth hogs, because phone lines aren't shared among households.