Users with the "Add Article" permissions are unable use the "copy" function in the Journal Portlet because the permissions are not checked properly. So essentially only the community administrator can use this function.
As part of this bug fix, the following method has been added to JournalArticleService
public com.liferay.portlet.journal.model.JournalArticle copyArticle(
long groupId, String oldArticleId, String newArticleId, boolean autoArticleId, double version, long plid)