While it is possible to create a custom link type for prerequisite/postrequisite issues, it is limited in usefulness by the following:

1) There is no way to search for issues based on links (eg: Search for all issues with a prerequisite issue that is/is not resolved)

2) There is no way to generate a report or gantt chart (MS Project format?) based on those links

3) It would be ideal if issues had an "active" or "inactive" state beyond the "fix version" roadmap. We often are entering issues into JIRA that need to be remembered, but not on an employee's active list just yet. (for now, we have a workaround in a custom priority called "not now". Surely we can do better!) In my view, an issue with prerequisites should be considered "active" only if all the prerequisite tasks have been closed. At that point, a user who searches for issues assigned to them would find a new issue and could react appropriately.