text: Being "Black Listed" isn't a formal list.  It refers to a bad reputation that makes someone a less than desirable employee, making it hard for them to get employed.\n\nThe most famous was the Communist witch hunt.  In this instance, it was created by the government.  Many intellectuals, actors, writers, etc. found themselves unable to get employment because the refused to take part in the witch hunt.  Government agencies threatened harassment if any employer hired these people.\n\nThe government has also made these "Virtual black lists" for other reasons.  Howard Stern could claim this.  In early days, many comedians found themselves in this situation because their routines were considered too racy.\n\nSome scientists have also claimed government harassment because they spoke out against the governemnt policies or left government employment.\n\nSocial institutions can also create a virtual black list.  In these instances, they typically try to use economic pressure to prevent employment of individuals.  \n\nA person can be black listed if they gain a bad reputation in their industry.  For example, if an engineer or architect designed a bridge, building, or other structure that failed, they might not be able to get employment in their industry, even if they are cleared later.\n\nA person can also be "Black listed" for famous behavior or notoriety shunned by society.  For example, if someone was accused of a well publicized crime and later found innocent, the reputation of the accusation could follow them making employment difficult.\n\nIf a person has had a lot of difficulties at several employers, they can find themselves black listed as their bad reputation follows them from 1 employer to the next.\n\nYou can also find yourself black listed in a company because of a well known goof up or just because a higher level manager doesn't like you.  This can effect pay raises, how you are treated, and your general level of happiness in a company.\n\nIn summary, to be effective, black listing requires at least 1 of the following:\n-Government involvement\nInvolvement by a social institution (such as religion)\n-Well publicized notariety\n-A small community (a small town)\n-A small industry with few employers