What a difference a year and a half makes. By now, Dalton McGuinty must be wishing he had resigned in 2011 and let another leader fight the last election as Ontario’s Liberal leader. Had he left at that relatively high point, McGuinty could have sailed out of Queen’s Park with a powerful legacy of improvements, especially in the health and education of everyday people.

But by fighting for a third mandate, and then hanging on as Ottawa South’s MPP after stepping down as premier last October, McGuinty overstayed his welcome with Ontario’s voters. He left himself vulnerable to an emboldened opposition that uncovered the mess behind the Liberals’ costly and nakedly political gas plant cancellations. While details of that wasteful spending could not — and should not — have been kept quiet, it’s unfortunate for McGuinty that he is departing at a time when his achievements are overshadowed by the mistakes of his final year in power. Even now, though, it would be wrong to let those undoubted errors in judgment erase all of his public good.

Taking the long view of his nine years in office, McGuinty can rightly claim a solid record of achievement in areas that matter most to Ontarians. Premier Dad, as the Queen’s Park reporters called him, was responsible for impressive improvements to the education of Ontario’s youth, especially those who needed an extra hand up in life. These changes, from full-day kindergarten to improved high school graduation rates, have had a dramatic impact. Many young people are thriving in careers today because the McGuinty government’s vision for Ontario’s education system helped them to succeed.

In health care, the Liberals invested heavily in hospitals, doctors and nurses. Gone are the dramatic shortages of family physicians. Emergency-room wait times are significantly shorter. On the environment, Ontario established greenbelt protection in the greater Toronto region, protecting Canada’s richest farmland from urban sprawl.

Ontario has made great strides towards a modern — and greener — energy system, raising hydro bills but also protecting residents from an unreliable system that left many in the dark. Indeed, it was this move toward energy modernization, the embracing of gas plants over dirty coal, that proved to be McGuinty’s final undoing.

It was a calculated political decision to cancel the plants in Mississauga and Oakville after a local outcry, although at the time the Progressive Conservatives said they would do the same. The cost of those decisions is now reaching a shocking $585 million, a terrible loss of tax dollars that could have helped to pay down the deficit or further improved health and education.

It cannot have been easy to stay on as a backbench MPP throughout these last few months. Perhaps McGuinty did it to help his successor, Premier Kathleen Wynne, avoid a risky byelection. After all, a loss could have further weakened her fledgling minority government. In any case, Wynne now has three seats instead of two to fill in byelections. And McGuinty’s departure from political life may well help her to make a definitive break between his government and hers.

Certainly, McGuinty did not spend much time at Queen’s Park. He duly appeared before the legislative committee scrutinizing the gas plant cancellations. And when Ontario’s Information and Privacy Commissioner reported that senior political staff in his government had illegally deleted emails related to those decisions, McGuinty denied any knowledge of those acts. But no matter what he knew, he cannot escape political responsibility for that misbehaviour.

None of the emerging details can be excused. But over a long political career, a leader can be responsible for both terrible mistakes and exceptional achievements. Ontarians, especially now, may well refuse to forgive him for his government’s missteps and misdeeds. But they should also acknowledge that for a long time, McGuinty managed to accomplish a whole lot of good for many people.

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