One of the most troublesome rules concerns whether or not to capitalize titles when they follow a person's name or are used in place of the name. According to many authorities, only the titles of "high-ranking" officials and dignitaries should be capitalized when they follow or replace a person's name. But how high is high? Where does one draw the line?
Authorities draw the line at various places. It helps to understand that the answer to how high is high will depend on where you stand in relation to the person named.
At the international level, a lot of us would be willing to bestow initial caps on the Queen of England, the Pope, the Secretary General of the United Nations, and people of similar eminence.
At the national level (in the U.S.A.), many of us would agree on honoring with caps the President, the Vice President, Cabinet members (such as the Attorney General), the heads of federal agencies and bureaus (such as the Director or Commissioner), but probably not lower-ranking officials in the national government. (However, if you worked in Washington and were closer to those lower-ranking people, you might very well draw the line to include at least one of them.)
At the state level, all would probably agree to honor the Governor and even the Lieutenant Governor, but most of us would probably refer to the attorney general of the state in lowercase (unless, of course, we worked for the state government or had dealings with the official in question, in which case we would write the Attorney General).
Because most people who write style manuals are removed from the local levels of government, they rarely sanction the use of caps for the titles of local officials; but anyone who works for the local government or on the local newspaper or has direct dealings with these officials will assign to the titles of these officials a good deal more importance than the writers of style manuals typically do. Indeed, if one were writing to the mayor, one would refer to the Mayor. But if one were discussing this official with someone else in writing, one would refer to the mayor.
In the final analysis, you should establish an appropriate style for your own writing in a given context, and follow it consistently within that context. Keep in mind that if you do have a custom style guide for your company, you can register it on the ProofreadNOW server and our editors will use it as we edit for you.
This week's info on capitalization is from The Gregg Reference Manual.