When you click on the link to the petition, you will see a page with the following buttons below the petition:
You cannot sign the petition until you log in to your whitehouse.gov account. You must click on one of the two blue buttons to either sign in to an existing account or to create a new account.
The “SIGN THIS PETITION” button is greyed out. It behaves like a link when you hover over it, but no amount of clicking on it will get you anywhere. You must first choose one of the two blue buttons. When you finally go through with all the rigamarole, then the “SIGN THIS PETITION” button lights up and you can click on it.
In a well thought out web design WhiteHouse.gov has also put some greyed out buttons below the ones that I have shown. These are for promoting the petition on Twitter or Facebook. Having gone through the problem with the greyed out “SIGN THIS PETITION” button, you might think that the greyed out “twitter” and “facebook” buttons are also inactive. You would be wrong in making this natural assumption. If you click on either of these two buttons, they will take you to either Twitter or Facebook.
With a user interface design like this, you have to wonder if the Whitehouse really wants any petitions.