More or less in decreasing order of importance:

• rel is misused. Instead of <span rel="x"> it should be <a href="#x">; use <a href="#"> for the undecided ones. You could start using the hashchange event too to make things a bit nicer.
• <aside> is not used semantically.
• Put "use strict"; at the top of your JavaScript.
• That would give you errors if you did something silly, like, say, forgetting a var and thus creating a global variable targ or scrollTo.
• preventDouble is not used.
• In fact, your code could use some JSHinting for both correctness and style.
• The section#decisionList seems to be silly wrapper used only for styling; get rid of it.
• JavaScript at the bottom of the page (before </body>) for best performance. This would also get rid of the need for the $(document).ready wrapper, but of course you'd still want to use an IIFE to avoid polluting the global scope.
• type="text/javascript" is not necessary; nor is type="text/css".
• Any reason for using opacity instead of visibility?
• It's customary to prefix (or sometimes suffix) cached jQuery variables with $, so $decisionDetails, $targ, etc.