No criminal charges will be brought over 14 police inquiries into Conservative party spending in the last general election. Around 30 Tory MPs and party agents were being investigated for expenses fraud. The allegations concerned spending over “battle buses” transporting activists into marginal seats. Expenses were wrongly filed as national spending rather than spending on individual constituency campaigns.

The Tory MPs in question have been waiting in suspense for the CPS to rule on their future. It has decided not to press charges, because it can’t prove the expenses were filed this way deliberately:

The 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.”

Because agents say they believed the costs were part of the national campaign, “it would not be possible to prove” any agent acted knowingly or dishonestly, he added.

It would have been a blow to the party’s election campaign if the candidates under investigation had to stand aside, as the deadline for selecting general election candidates is tomorrow. It would also have been bad news for Theresa May, whose general election campaign messaging would have been derailed.

One theory for why May called this election is that it is partly to cushion the blow prosecutions would have had on her party in Parliament. I explained the consequences this could have had for her majority when the fraud allegations emerged this time last year.

They’re not fully in the clear though. The accounting of expenses in Thanet South, where Ukip leader Nigel Farage failed to get elected, remains under consideration; the file from Kent police was only recently given to the CPS. It will be decided before polling day. Nick Timothy, May’s chief-of-staff, was based in the battleground seat, which could make things uncomfortable for Downing Street (though he is not accused of wrongdoing).

So what happens now? Many on the left will be disappointed by the CPS’s decision, hoping that criminal charges could have brought about a turning-point in the Conservative party’s fortunes. But they should keep their chins up. There has been a reluctance within Labour to make too much political hay with this story, as it could open all parties up to scrutiny of their expenses claims during the general election campaign. All parties bus in activists to marginal seats, after all, and all parties are subject to the same complicated election spending rules. In 2015, Labour had its “Labour Express” and “pink bus” campaigns.

Even if the CPS had ruled against Tory candidates today, I hear that even left-wing campaigners like Momentum members were reticent about bringing it up on the doorstep to denigrate the Tories. Drawing attention to dishonesty in political parties generally works to make voters lose trust in politicians in general – not just Tory ones. And as I discovered in England’s most marginal constituency this week, levels of distrust are sky-high, even among voters who approve of Jeremy Corbyn’s policy platform.

In the long-term, this outcome should get the ball rolling for reforming the ridiculous election spending rules. As I’ve argued before, it is a nonsensical system that the Electoral Commission has oversight of regulating national campaign spending, but local spending is down to local police forces. The Electoral Commission has been calling for four years for the power to enforce candidates’ spending rules.

Reforming the rules would need to address how a party’s overall spending affects the marginal seats it is targeting, and dilute the rather arbitrary distinction between national and local campaigning. It is also time to ask why British politicians are having to navigate a system that forces them to spend less than half per vote than what they did, in inflation-adjusted terms, at one point in the 19th century. A change that could benefit Labour and the Tories.