The subject has come under the spotlight at the IAAF World Championships in London after two-time offender Justin Gatlin beat eight-time Olympic champion and crowd favorite Usain Bolt to 100m gold on Saturday.
Gatlin was booed every time he was introduced to the crowd at the London Stadium at the weekend, with spectators also jeering once it was clear that the 2004 Olympic champion had won 100m gold and ruined the retiring Bolt's farewell.
Coe has previously blamed the World Anti-Doping Agency (WADA) and legal systems worldwide for Gatlin's return to the sport after two doping violations.
"I have always, always viewed a life ban as the ultimate sanction," Coe told CNN's Don Riddell.
"We made an error a few years ago in allowing ourselves to go from a four-year to a two-year ban to maintain within the spirit of standardization within WADA -- that was an error.
"We should never have done that. We have tried life bans consistently, but we have failed in various courts."
On Sunday, former Olympic heptathlon champion Jessica Ennis-Hill, heavily pregnant with her second child, received heptathlon gold from the 2011 World Championships after the original winner, Tatyana Chernova, was subsequently found to have doped.
Advances in technology means WADA can now test for previously undetectable illegal substances.
Ennis-Hill is one of a number of athletes to have been re-allocated medals and Coe insisted that these ceremonies were proof that the IAAF was taking the matter seriously.
"The very fact that we are re-presenting medals to athletes from the 2009 World Championships in Berlin tells me that we're not throwing this under the carpet," he said.
"The public want to see that. I am determined to get those records and those medals back into the hands of their rightful owners. My only sadness is that they were robbed of that opportunity in the first place.
"Yes, we take this really seriously but the history of this is not one we are going to walk away from, nor should we. I'm not in a position to recast the past, but I can shape the future."
Watch the video at the top of the page for the full interview.