The dictionary definiton of “coercion” is: “the use of force to persuade someone to do something that they are unwilling to do”.

In Scots law, coercion can be a “complete defence” (i.e. if it is accepted, then the accused should be acquitted of the offence charged) in limited circumstances.

The starting point is generally that that the accused will accept, as a matter of fact, having acted in the manner alleged. The defence relates to the motivation for their actions. It could be argued that someone acting under coercion is not acting of their own free will, or, alternatively, that a coerced person could never have the required mens rea to, for example, assault a third party. Either way, coercion looks behind the alleged offence itself.

It has been said (in the 1991 case of Collins v HMA) that coercion is not available as a defence to a charge of murder, “because of the supreme importance that the law affords to the protection of the human life…[Nobody has] the right to choose that one innocent person should be killed rather than any other person including himself.”

The principles of coercion are set out in the case of Thomson v HMA from 1983:

Thomson v HMA [1983 JC 69]

“[I]t is only where, following threats, there is an immediate danger of violence, in whatever form it takes, that the defence of coercion can be entertained, and even then only if there is an inability to resist or avoid that immediate danger. If there is time and opportunity to seek and obtain the shield of the law in a well-regulated society, then recourse should be made to it, and if it is not then the defence of coercion is not open. It is the danger which has to be “immediate” not just the threat.” – Lord Justice Clerk Wheatley at p77

So, for a defence of coercion to succeed, the accused must have been forced into acting in the manner libelled due to:

  1. a threat of immediate harm, and;
  2. committing the crime is the only way to avoid the harm.

In other words, if there is an opportunity to escape the situation (e.g. by running away or going to the police station), then the defence of coercion will almost inevitably be unavailable. A threat of future harm (e.g. “Rob that bank by the end of next week or I’ll kill you” will, in the vast majority of circumstances, give the threatened person a chance to escape and/or seek help from the authorities; committing the crime is not the only option available to them.

The threat of harm must be serious – “Rob that bank or I’ll kick you in the shins” wouldn’t cut it.

The accused’s actions are to be judged objectively. In addition to the two crucial factors above, the crediblity of the defence can be judged by the extent of the accused’s role in the crime, the disclosure of the fact of coercion, and the return of any proceeds of the crime (e.g. in the circumstances of a coerced theft) as soon as possible.

The bar is set deliberately high. Coercion defences are very rare in practice.