John C. Munro, a former federal cabinet minister and longtime scrappy ex-Liberal politician who always fought for the underdog, died of a heart attack Tuesday at his Hamilton home at the age of 72 years. Born and raised in Hamilton, Ont., he graduated from Osgoode Hall Law School and began his political career as a city alderman in 1954 at age 23. He first ran for federal politics in 1958. After his defeat, he spent four years building up a successful labour law practice that won him friends and influence in the blue-collar town. By 1962, he was popular enough to win the federal seat of Hamilton East, which he held for eight elections, until his retirement in 1984. He built a powerful political machine, becoming known for his ability to win government funding for projects in his riding. He pumped nearly $85 million into harbour development, assistance for companies and a major expansion of the Hamilton airport. In 1968, Mr. Munro was appointed minister of health and welfare by then-prime minister Pierre Trudeau. In this portfolio, he suffered the mockery of cartoonists for his two-pack-a-day smoking habit, hard drinking, and ceaseless coffee consumption. But he was a hard-working minister, ushering in the Canada Pension Plan and medicare. In 1972, he was appointed labour minister, a post in which he achieved some of his greatest accomplishments in establishing worker retraining programs. But he was forced to resign from cabinet in 1978, when he telephoned a judge to vouch for the character of a constituent who was charged with assault. The telephone call contravened guidelines laid down by Mr. Trudeau in 1976 to safeguard the independence of the judiciary. He returned to cabinet as minister of Indian affairs and northern development from 1980 to 1984. He ran unsuccessfully for Liberal leadership against John Turner in 1984. He was given a patronage appointment to the Canadian Transport Commission by Mr. Trudeau later in 1984. In 1989, he was falsely accused of funneling $1.5 million in government grants to aboriginal organizations to back his own leadership bid. By 1991, a judge cleared him of all charges after he'd spent $200,000 in legal fees. His career took a toll on his personal life, with his first two marriages ending in divorce. He married a third time in 1993, by which time he had adopted a healthier lifestyle. He had two daughters, Susan and Anne, from his first marriage, and two sons, John and Richard. In 2000, at the age of 69, he was back in politics, running unsuccessfully for mayor of Hamilton and promising to revive the city's decaying urban core. He is survived by his wife Barbara, four children and four grandchildren.