Is it possible to legally prohibit someone from linking to specific pages on your website?

Question

By linking I meant to give exact instructions about how to find a specific page on the site, for a user with enough privilege. It can be a URL, or a demonstration of where you should click, etc.

The site don't have to be open to everyone. But they had no informations about their user's real identity. Everything they could get is at most an "I agree" checkbox during registration.

I'm not asking about whether they can remove the user posting or using the link, but is it possible to legally request removing the link itself (in other sites)?

My first guess is no. I think it is not directly related to copyright as the user didn't post the content, and your terms of service cannot affect other sites. But then I feel there are some quite similar things seemed possible, and someone must be already trying to do this. So is it? If yes, what are those terms called (a part of the copyright license or terms of service, or something else)?

@apsillers pointed out this may have something to do with the contract law. I think indeed this can be done between companies, or companies and employees. But (1) is it still effective if the site just let users to agree to the terms online? (2) If a user did it anyway, I think you can only remove the user in your site, or in theory you can let the user pay. But you still cannot remove things in other sites, because those sites didn't agree to the contract. Is that right?

I'm thinking about a license like this:

• You can use the ideas in whatever way you want (they are not patented; or maybe they are, but the fact your site is describing them cannot be patented).
• You cannot copy the articles directly (there is copyright).
• You cannot refer to the explanations in this site in formal documents of a company, or prove this site has promoted this idea. Or a weaker term: you have to pay to do that.
• You can rewrite the whole things, or don't leave explanations, or whatever.

This is indeed a bad idea which I thought it must be disallowed at first. But it seemed to be weaker than what a company can have with their employees.

Answer 1

No.

You are correct in that this is not related to Copyright. Copyright is meant to protect expressions of an idea.

An URL is simply an address, like a street address. Can you legally stop people referring to your home address? No. Can you legally stop people from passing by and looking at your house on the street? Also no.

A famous case related to hyperlink is Ticketmaster v Tickets.com (2000). Tickets.com used information Ticketmaster's website and deep-linked to there. The ruling established that:

1. use of information is not infringing
2. hyperlinking cannot be copyright infringement because no copying is involved.
3. deep linking is not unfair competition

If you feel that it is necessary to avoid people linking to specific pages of your site, you may consider accomplishing this technically.

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UPDATE

It does not matter whether your site is meant to be public or not. For example, an knowledge base meant to be shared internally in an organization, but accessible on the internet since staff are geographically distributed.

Again, you may think of it like a street address. A private corporate building meant for employees only. An address, like Room C, 16/F, Example Corporate Complex, 4321 Lucky Avenue can be shared like any other address. You cannot demand people to never refer to your office address. You can, however, setup a security post at the entrance and only allow certain guests to visit you.

In the case of a website, you may state in your terms that one cannot share access information to any external parties. This will include the sharing of any authentication data (e.g. password) which can be used to access content.