The Crown Prosecution Service has ruled out charges against 14 Conservative candidates over 2015 election spending, with one further case still under consideration.
The candidates, all of whom sat as MPs during the previous parliament, had been under investigation over claims that they broke spending rules during the campaign, with the dispute focused on how cash used for the Tory "battlebus" campaign was reported.
The party has argued that expenses relating to the battlebus should be included in national, rather than local, figures. This would mean that spending could be excluded from strict local limits.
However, prosecutors today confirmed that there was "insufficient evidence" to pursue the case further.
CPS head of special crime Nick Vamos said: "In order to bring a charge, it must be proved that a suspect knew the return was inaccurate and acted dishonestly in signing the declaration.
"Although there is evidence to suggest the returns may have been inaccurate, there is insufficient evidence to prove to the criminal standard that any candidate or agent was dishonest."
A separate case, relating to Thanet South MP Craig Mackinlay, remains under consideration following a submission by Kent Police.
Referring to the ongoing investigation Vamos said: "No inference as to whether any criminal charge may or may not be authorised in relation to this file should be drawn from this fact and we will announce our decision as soon as possible once we have considered the evidence in this matter."
Mackinlay had previously interviewed by police under caution. He has denied any wrongdoing.
The electoral commission has already investigated Conservative spending at the 2015 General Election, fining the party £70,000 for missing and unreported payments.
Labour and the Liberal Democrats have separately been issued with £20,000 fines over their spending in the 2015 campaign.
Conservative Party chairman Patrick McLoughlin said: "After a very thorough investigation, we are pleased that the legal authorities have confirmed what we believed was the case all along: that these Conservative candidates did nothing wrong. These were politically motivated and unfounded complaints that have wasted police time. We are glad that this matter is finally resolved.
"A number of false and malicious claims continue to be spread on the internet. People should be aware that making false claims about a candidate’s personal character and conduct is an electoral offence, as well as being defamatory."
Labour leader Jeremy Corbyn said he was "interested and surprised" by the verdict, and expressed his belief that the Electoral Commission, the Crown Prosecution Service and the director of public prosecutions are all independent.
"Our election laws must be enforced and adhered to," Corbyn added.