Hi,

I am an attorney working for the government.  The duties of my job position mostly involve considering legal requests called "petitions."  My job title is "Petitions Attorney."  I am unclear as to when the first letters in "Petitions Attorney" should be capitalized.

This is a matter of style and convention rather than of grammar. The usual convention is not to capitalize, unless it is in a context where you really want to stress that this is your job title.

eg I ask you what kind of work you do. Here, I don't really care about your official job title.

eg I am reading the employment section of your resume. I expect it to tell me the job titles for your previous periods of employment.

Finally, as a general comment, I would say that in modern English, writers try to avoid having a lot of capitals in a sentence. Except, of course, at the start of a sentence.

Are the following correct or incorrect? I wouldn't say they are wrong, but I don't think I'd capitalize.

   I am a petitions attorney.  

   My coworkers include 10 other petitions attorneys.

   Petitions attorneys are a type of attorney working for the federal government.

   Petitions attorney John Smith has worked for the government for 10 years.

    Five petitions attorneys were transferred from location X to location Y.

I look forward to learning the correct way to capitalize the words in the sentences above.

Are you sure your title uses the plural word 'petitions'? Usually, in such compound expressions, the first noun is singular.

eg We say 'car mechanic' but not 'cars mechanic', 'book seller' but not 'books seller'.

Best wishes, Clive