The dreaded realisation that you have not complied with a rule or practice direction. Your life flashes past you and a cold sweat breaks out. Out comes rule 3.9 and the new criteria, Mitchell, a call to the insurers… Or perhaps r. 3.10 applies?
“Where there has been an error of procedure such as a failure to comply with a rule or practice direction- (a) The error does not invalidate any step taken in proceedings unless the court so orders…”
There are some nuggets to be found in the recent case of Integral Petroleum v SCU-Finanz AG  EWHC 702 (Comm) in which the scope of r.3.10 was explored by Popplewell J.
In Integral the parties agreed an extension of time by e-mail for the service of the Particulars of Claim by 28 days to 6th June (in fact 28 days would have given until 10th June). The Particulars were served by e-mail at 18.41 on 10th June meaning they were deemed served out of time. SCU challenged validity of service on the grounds that e-mail was not a permitted method of serving and, in any event, service was late. No Defence was filed and Integral obtained judgment in default.
Under r.6.20 e-mail may only be used to serve documents other than the claim form where a party has indicated that he or she is willing to be served by e-mail. SCU had not given such an indication.
The judge found that the error of procedure in serving the Particulars of Claim by e-mail was a failure to comply with a rule or practice direction which fell within r. 3.10. Accordingly under r. 3.10(a) such service was a step which was to be treated as valid:
He considered that the rule was to be construed as of wide effect so as to be available to be used beneficially wherever the defect has had no prejudicial effect on the other party. The method of service was recognised but the formalities necessary to make it a permitted method had not been concluded.
He drew a distinction between service of the originating process and service of Particulars of Claim and thought a narrower approach to r. 3.10 should be taken when dealing with the originating process.
r. 3.10 was particularly apposite for treating as valid a step whose whole function was to bring a document to the attention of the opposing party where such function has been fulfilled - he said “It prevents a triumph of form over substance”.
The judge also found that the rule applied in relation to service of the Particulars of Claim 5 days out of time.
The upshot of all of this was that Integral could not set aside judgment as of right but the judge did set it aside under r. 13.3.
Rule 3.10 is one to bear in mind when you next find yourself having a scrape with deadlines, procedural formalities etc. In the light of Mitchell the caselaw on this rule is likely to expand greatly.