No one knows the rules at City Hall better than George A. Nilson, Baltimore's top lawyer.

“You can't engage in political activity during working hours,” the city solicitor said in an interview last week. Nilson's office even recently sent a memo to city workers warning against using government equipment for politics.

That's why Nilson said he is “embarrassed” he inadvertently sent an invitation to friends from his government email to a campaign event for Democratic mayoral candidate Elizabeth Embry.

“I never do political stuff on the job during working hours,” Nilson said. “And I never knowingly use city email” for political activities.

Ever the lawyer, Nilson keyed on the word “knowingly.”

Nilson said he sent three batches of emails from his personal iPad to invite people to a birthday-party-cum-campaign-fundraiser for Embry at the Hippodrome Theatre on March 14. Two of the batches were sent from his Gmail account, he said. But a third, on March 10, came from his city government address. The time on the email was 6:30 p.m., after official work hours.

“How in the hell my city email address was the sender, I don't know,” he said. “I'm embarrassed that what happened happened.”

But, he added, it was “total inadvertence.”

In the March 10 email, Nilson wrote that, “we enthusiastically join Elizabeth's mom in inviting you to this combined Birthday and Campaign event for the person who should be the City's next Mayor. Funds are vital as they feed and support the boots on the ground. Let's move the City into the competent hands of the next generation.”

Since November, the city solicitor for Mayor Stephanie Rawlings-Blake's administration has contributed $1,050 to Embry's campaign, according to campaign finance records filed with the state.

“It's no secret I'm fan of hers,” Nilson said of Embry, whom he hired to work in the city solicitor's office.

He's also been friends with her father, Robert C. Embry Jr., for years, he said.

“Other than the small check I left for Sheila Dixon at an event, otherwise I try to stay out of it,” he said.

Yes, Nilson also contributed $250 to Dixon's comeback campaign. The former mayor hired Nilson as city solicitor in 2007. (In that election year, Nilson contributed $1,000 to Dixon. For the record, the most he ever gave Rawlings-Blake was $400 in the 2011 election.)

“I think Sheila would make a good mayor,” he said. “But so would Elizabeth. It's an interesting time we live in.”

Rawlings-Blake said through a spokesman that all city employees could learn from the mistake.

“As government employees, all of us are aware that we must be careful with respect to what we are, or are not, permitted to do on government time or with government resources,” spokesman Howard Libit said in a statement. “However inadvertent or accidental, the Mayor understands the significance of mistakes like this, particularly by the person whose position makes him the standard-bearer for ethical conduct. This incident can serve as a useful reminder to all employees about the importance of being vigilant in an election year.”

—Doug Donovan