Conspiracy Offences Defence

The prosecution should identify the alleged agreement with precision: what offence was to be committed, the period of the conspiracy, who the alleged parties were, what each defendant is said to have agreed to, and the evidence from which participation and the required state of mind are inferred.

Section 1(2) of the 1977 Act also imposes an important knowledge or intention requirement where the substantive offence can be committed without knowledge of a particular fact or circumstance. At least the defendant and one other party must intend or know that the relevant fact or circumstance will exist when the planned conduct takes place.

Conspiracy is distinct from secondary liability or “joint enterprise”. Conspiracy concerns agreement to pursue criminal conduct; secondary liability concerns intentionally assisting or encouraging another person’s substantive offence. A case may raise both concepts, but the prosecution must prove the correct legal route against each defendant.

For an allegation involving money laundering, see our money laundering defence guide.

Conspiracy cases frequently rely on circumstantial and digital evidence: encrypted or ordinary messages, call data, contact patterns, cell-site or location evidence, CCTV, surveillance, vehicle movements, meetings, financial transfers, cash, business or company records, travel, weapons or drugs evidence and the acts of alleged co-conspirators.

Digital attribution is often critical. A device, SIM, account, username or handle must be linked reliably to the person said to have used it at the relevant time. Selected messages should be read within complete threads and against the wider chronology before their meaning is treated as established.

Reasonable enquiries may include device and account attribution; obtaining complete message threads; testing cell-site, location and travel evidence; examining legitimate financial or business records; identifying CCTV or witnesses; separating the chronology defendant by defendant; and checking whether alleged meetings or communications are equally consistent with non-criminal relationships or activity.

In a large multi-defendant case, evidence should be mapped individually. Material proving that one person committed an offence does not automatically prove that another person agreed to it. The defence should identify which communications, acts and inferences are actually relied upon against this defendant and which belong only to other defendants.

Statutory conspiracy is triable only on indictment. Serious investigations may involve arrests across several addresses, search warrants, seizure of multiple phones and computers, financial investigation and lengthy digital schedules before a charging decision.

At the pre-charge stage, focused representations may be appropriate where the alleged agreement is overstated, device or account attribution is weak, communications have been read out of context, the chronology does not support participation, or a defined financial, travel, witness or digital enquiry could materially affect the charging assessment.

If charged, conspiracy cases commonly involve substantial prosecution schedules, co-defendant material, disclosure issues, expert evidence and detailed Crown Court case preparation. Drug, fraud and money-laundering conspiracies may also generate confiscation proceedings under POCA.

Preserve complete communications, financial records, travel and location material, company or employment documents and anything objectively explaining contact with alleged co-conspirators. Keep search records, property receipts, interview material and bail documents.

Do not delete, alter or wipe devices or messages. Do not coordinate accounts with co-defendants or contact witnesses contrary to bail conditions or legal advice. Prepare a chronology of your own movements, communications and legitimate reasons for contact while records are still available.

Send the suspected or charged conspiracy offence; alleged conspiracy period; prosecution case summary if available; your alleged role; police force and officer; interview, bail or RUI status; next date; search/seizure paperwork; phone or account schedules; key communications; financial or business records; location/travel material; and details of the alleged co-defendants.