I have read a lot on the subject and also the forum, and I am still confused a bit in regards of my situation. I was arrested, charged with misdemeanor, my understanding that I was on diversion program (as there is no guilty plea on my docket report, had to perform the community service, upon completion the charges were dismissed). I have a lot of questions. If you can help me at least with some, would greatly appreciate it. I have been working abroad after the misdemeanor happened 4 years ago and I am thinking to come back to the US; thus am wondering if I will pass the background checks with the US companies.

First of all, I found out that I can legally say "no" to a question about my criminal background since my case was dismissed (Californian penal code 1203.4). Furthermore, somewhere I found that an employer cannot not to hire me because my case was dismissed. Not clear here,

Does this apply to the government companies and the private companies can do whatever they want in terms of setting up their hiring procedures? If yes, do you have an experience of being hired by fortune 500 company with a dismissed misdemeanor charge? Do you have an idea what generally HR policies are in big companies? I do not work in financial services industry where the regulations might be tougher.

Also, the big companies normally outsource the background screenings to third parties, which I understand normally fall under FCRA regulations (what they can do or cannot do). There are also California state laws that limit what employers can ask on the job application. In California an application may ask "job related questions about convictions except those that have been sealed, or expunged, or statutorily eradicated," but applications cannot ask "general questions regarding an arrest." However, that even the restrictions on reporting imposed by the FCRA do not apply to jobs with an annual salary of $75,000 or more a year. (FCRA 605(b)(3). Under FCRA says the records of arrest, from date of entry, after seven years cannot be reported.

My concern here is that my salary might be bigger than 75 k, so the FCRA regulations might not apply to me. Though, how often the third party background check companies do the background check for more than the last 7 years?

Additional question with the arrest:
In California, section 432.7 of the Labor Code, states "No employer, ..., shall ask an applicant for employment to disclose, ..., information concerning an arrest or detention that did not result in conviction, or information concerning a referral to, and participation in, any ... diversion program, nor shall any employer seek from any source whatsoever, or utilize, as a factor in determining any condition of employment including hiring, promotion, termination, ..., any record of arrest or detention that did not result in conviction". So, stupid question from my side: if I was ordered to complete the community service, it means I was convicted, right? Though, as I already mentioned, I have an impression that I was in diversion program (as there is no plea record at all) until I completed ordered community service and after my case was dismissed.
And also, I have doubts that an average criminal background check run by most of the companies without dip digging would include the arrest records. I saw one background check done on me by a fortune 500 company. There was one line "criminal records" and it was done for the previous 7 years. It was done prior to my misdemeanor.

I am sorry for a bit messy post, I feel I have a mess in my head after reading so much on the Internet about the subject that I am not that familiar with. In addition, I have my docket report from the court that have all the details of my case with the codes. If you need an additional information in order to help me, please ask. BTW, why I do not see an arrest info on my docket report? There is one line where arrest should be line "Case in pending status awaiting bail" and then "Own recognizance filed" -- I was let get on own recognizance.