Labour leader Sir Keir Starmer and his deputy Angela Rayner have not been issued with fixed penalty notices, Durham Police said.
Police launched an investigation into alleged Covid-19 lockdown regulation breaches while in Durham in April 2021.
But after concluding their probe, the force have now confirmed that both Sir Keir and Ms Rayner will not face any further action.
In a statement Durham Police said: "Following the emergence of significant new information, an investigation was launched by Durham Constabulary into a gathering at the Miners’ Hall, in Redhills, Durham on 30th April 2021. That investigation has now concluded.
Sir Keir Starmer and Angela Rayner PA
"A substantial amount of documentary and witness evidence was obtained which identified the 17 participants and their activities during that gathering. Following the application of the evidential Full Code Test, it has been concluded that there is no case to answer for a contravention of the regulations, due to the application of an exception, namely reasonably necessary work.
"Accordingly, Durham Constabulary will not be issuing any fixed penalty notices in respect of the gathering and no further action will be taken.
Both Sir Keir and Ms Rayner had previously promised to step down if they were found to have broken the rules Kirsty O'Connor
"The investigation has been thorough, detailed and proportionate. The final evidence supplied by participants from the local constituency was returned to Durham Police on 5th July and analysed by investigators against all the evidence before the investigation was concluded on 8th July 2022.
"In line with established national policing guidelines, we will not name or otherwise identify any of those present at the gathering, all of whom have been informed of the investigation outcome by their legal representatives."
Speaking after the announcement, Sir Keir tweeted: “I’ve always said no rules were broken when I was in Durham. The police have completed their investigation and agreed: there is no case to answer. For me, this was always a matter of principle. Honesty and integrity matter. You will always get that from me.”
While Ms Rayner added: “We’ve always been clear that no rules were broken in Durham. The police have completed their investigation and agreed, saying that there is no case to answer.
“Integrity matters in politics. The contrast with the behaviour of this disgraced Prime Minister couldn’t be clearer.”
A Labour Party spokeswoman said: “Keir Starmer and Angela Rayner have always been clear that no rules were broken in Durham.
“The police have completed their investigation and have agreed saying that there is no case to answer.”
Both Sir Keir and Ms Rayner had previously promised to step down if they were found to have broken the rules during a visit to the city, ahead of the Hartlepool by-election.
Sir Keir was videoed drinking a bottle of beer over a takeaway curry with colleagues in the offices of Mary Foy MP.
It later emerged Ms Rayner was also at the gathering, dubbed “Beergate” by some.
Labour’s Mary Foy, the MP for the City of Durham in whose offices Sir Keir Starmer was pictured drinking a beer over a takeaway curry with colleagues in April 2021, said she is “delighted” by Durham Police’s findings on the event after the “pressure of the last few months”.
“I am delighted Durham police have investigated and concluded that neither I or my team have a case to answer in relation to the work visit in Durham on April 30 2021,” she said in a written statement.