NEW YORK (MainStreet) — The percent of arrests related to marijuana possession has steadily increased even as some states have legalized recreational and medicinal use.

FBI data found that some 658,000 people were arrested for marijuana possession, which adds up to 42% of all drug arrests and 5.4% of all arrests for any offense; however, data is unavailable on expungements, whereby a first-time offender can have a record of his conviction hidden through state and Federal resources.

"Unfortunately, we do not have any statistics that we can share at this time relating to marijuana-related expungements," an FBI spokesperson told Mainstreet.

For criminal charges that occurred prior to legalization in Colorado, there is a retroactive application that allows for minor cannabis offenses to be expunged.

"It is exceptional, and I hope many states follow," said Tae Darnell, a cannabis lawyer. "You are required to go through the legal process to obtain the decree, but it only applies in-state with in-state convictions. Federally, marijuana use is still a crime."

As usual, money talks. Legal fees for expungement average between $1,000 and $2,000 depending on the state.

"You can file the paperwork yourself but most people choose to use a lawyer," Darnell told MainStreet.

Outside of Colorado, marijuana-related expungements in non-legal states require an order of the court.

"Expungements are usually only available for very low-level crimes, juveniles or for offenders who've completed a series of mitigation tasks like community service, drug rehabilitation or restitution," said Ann Toney, a marijuana law attorney in Denver.

In Oklahoma, attorney Todd Kernal charges $2,500 to $3,500 for a formal expungement.

"I have had clients try on their own and it normally backfires on them," Kernal told MainStreet.

Generally, if a prior marijuana charge could not be erased under general expungement principles, a state's legalization of marijuana won't help.

"Under age-old principles of constitutional law, new laws cannot generally work retroactively to address prior convictions or offenses," Toney told MainStreet. "Anyone with prior marijuana-related offenses in Colorado or Washington is still responsible and culpable for those crimes including anyone with a pending marijuana charged initiated prior to the official state date of legalization."

Many seeking expungements are doing so for employment purposes but just because marijuana is legal doesn't mean employers are required to hire people who have tested positive for marijuana use or have marijuana related offenses on their records.

"If these offenses were important to the employer before legalization, they probably are still important," said Nick Fishman, executive vice president of EmployeeScreenIQ. "Though the activity is now legal, it was illegal at the time of the offense, which one could argue speaks to character."

--Written by Juliette Fairley for MainStreet