"Tim has taken responsibility for it, so this isn't like we're going to have a trial or anything, to be candid with you," said Rod Pacheco, a former legislator and Riverside County district attorney who is Donnelly's attorney.
The Twin Peaks Republican, through Pacheco, pleaded not guilty to the charges at arraignment Feb. 24.
Pacheco said he met with prosecutors today, and has talked with them in the past, to explain threats made against Donnelly and other mitigating circumstances that should be considered in resolving the case.
"The justice system needs to mete out justice in a fair manner, taking into consideration various circumstances," Pacheco said, declining to comment on what he felt would be a fair disposition.
The case of a committed public servant bringing a gun to an airport by mistake is quite different than that of a gang member trying to sneak a weapon through airport security, Pacheco said.
Officials from the San Bernardino County District Attorney's Office declined comment today.
A pretrial conference today in San Bernardino County Superior Court was continued to next Thursday.
Donnelly, R-Twin Peaks, was charged with illegal possession of a loaded firearm and possession of a prohibited item in a sterile area in connection with the Jan. 4 incident at the Ontario airport.
Besides threats made against Donnelly, mitigating circumstances include his early acceptance of responsibility and the fact that the Assembly was holding its first floor session after a three-month break on the day of the incident, Pacheco said.
"It was easy for him to forget that he had put something in his computer case to protect his child from it," Pacheco said of the gun, described by officials as a loaded Colt Mark IV.
Donnelly, on the day he was cited, told reporters that he tended to be armed at the time because of death threats received after launching a referendum - ultimately unsuccessful - to overturn the Dream Act, a new law allowing some undocumented immigrants to qualify for state-funded college aid.
Pacheco did not elaborate on specific threats, but said they were "rather extensive" and delivered by e-mail, verbally and in-person.
"Tim is willing to speak out on controversial issues and, when you do that as an elected official, people get mad at you - and sometimes they're irrational and they threaten you," Pacheco said.
"(Donnelly) has had those threats. And, you know, Tim has got a young family and a wife, it's not just him anymore. He's not a single guy, he hasn't been for a long time. He has an obligation to his family to protect them."
The two counts against Donnelly carry maximum jail sentences of one year and six months, respectively, although judges are free to impose far lighter sentences based on circumstances. Each charge also carries a potential $1,000 fine.