It's disappointing that neither City Council nor the city's independent Ethics Board feels very strongly about the legal requirement that Council members attend an annual ethics training session. While City Hall has made strides since its groundbreaking ethics law was passed in 2005, opportunities for ethical breaches that border on being criminal, when they don't cross the line, have not been eliminated. Vigilance is essential.

The ethics classes are required for all Philadelphia elected officials, city cabinet members, department heads, and board and commission members. But staff writer Tricia A. Nadolny reported Thursday that of the 12 Council members who have been in office at least five years, none had attended more than two classes.

Part of the fault is the Ethics Board's, which held only one course in 2013 and skipped the training in 2015.

The city's approach to ethics training has been so lackadaisical that Councilman Kenyatta Johnson didn't even realize that a requirement for it existed. He introduced a bill last week that would require ethics training for Council members every four years only to be told it was already required annually. "Every time we get reelected, we should take a class," Johnson said. He's right: Because it's the law.

And that law wasn't easy to achieve. As a councilman, former Mayor Michael Nutter met a wall of resistance when he tried to get ethics reforms enacted 12 years ago. Council members protested that new rules weren't needed. Only after a fellow member, Rick Mariano, became the target of a corruption investigation did they seem to change their tune. Mariano was convicted, sentenced to six years, and served five for taking bribes.

While Council has avoided any similar embarrassments, the city has suffered more recent ethical lapses by public officials, including the 2015 indictments of five then-current and former state representatives and a traffic judge for taking bribes from a federal informant. All but one eventually pleaded guilty or no contest. Every one of the defendants had ties to City Hall through the local Democratic Party.

Further evidence of the ethical minefield called Philadelphia politics was on display in the federal fraud trial of State Sen. Larry Farnese. Although he was found not guilty Thursday, it was disturbing that his defense for allegedly paying a bribe to win a ward leader election was that his behavior was common in local politics.

Clearly, Council members aren't the only ones who need to be taught that just because something is legal doesn't mean it's ethical. The Ethics Board shouldn't skip any training sessions, and Council President Darrell Clarke should make sure all of his members obey the law.