Is deliberate radio interference justified in self-defense or defense of others?

Question

Deliberate radio interference is normally, if not always, illegal. Is self-defense or defense of others a valid justification? If Alice hears Bob and Bill using radio to plan a violent crime, is it legal for her to jam their signals? If disrupting the planning is not legal, what if they have a remote-control bomb and she is jamming the bomb's trigger signal?

Answer 1

canada

As explained in a previous answer, the defences of "self-defence" and "defence of another" are available defences to justify or excuse any act that would otherwise constitute "an offence" in Canada.

If it wasn't clear before 2012, amendments in 2012 to the self-defence laws in Canada made it absolutely clear that any offence may be justified or excused by self-defence or defence of another, as long as the substantive elements of the defence are made out. The Supreme Court said in R. v. Khill, 2021 SCC 37:

The accused’s response under the new law is also no longer limited to a defensive use of force. It can apply to other classes of offences, including acts that tread upon the rights of innocent third parties, such as theft, breaking and entering or dangerous driving.

Answer 2

Only under very limited circumstances

germany

Germany regulates Self defense in §32 StGB. To have a situation of Self Defense, sentence 2 is relevant:

(2) Notwehr ist die Verteidigung, die erforderlich ist, um einen gegenwärtigen rechtswidrigen Angriff von sich oder einem anderen abzuwenden.

(2) Self Defense is the defense, which is required, to prevent/stop/end a current [and] illegal attack against yourself or someone else.

This is technically unlimited in breadth but has two main limits:

• Required to prevent/stop [erforderlich um abzuwenden]
• current [and] illegal attack [gegenwährtiger rechtwidriger Angriff]

A planning scenario is not Notwehr

The requirements of Notwehr mean that you can not prevent someone from planning an attack, as that is not a current and illegal attack - the attack is not yet taking place. Also, it is very unlikely that jamming in this situation would be a way that is triggering the required "Erforderlichkeit" (required to prevent), and thus was "geboten" (necessary). In fact, it would vastly violate the concept of Gebotenheit in the situation OP poses. Note that Gebotenheit and Erforderlichkeit might be translated by necessity or exigency, but that is a bad match, as it only covers the top layer. Gebotenheit covers:

• Requirement for your chosen action to happen
• Proportionality of the action taken
• Appropriateness to solve the situation.

Under Gebotenheit, you can not stab someone that has turned away from you and ended their attack on you - your action is no longer appropriate, proportional, or required. Likewise, Gebotenheit tells that jamming radio is neither a proportional, nor appropriate means to prevent an attack that is not even happening right now.

When might Gebotenheit exist?

However, there might be situations where jamming might trigger the two required factors. For example, take a remote-controlled bomb: the bomb is, at the time, a current and illegal attack, and jamming is required to prevent/stop that attack from happening. In that situation jamming is allowed.

...Germany's Solution to the Trolly

But now, a quirk of the german legal system surfaces: Germany actually solves the Trolly problem in legal circles in its own way: If you have to decide between two equal rights with action or inaction, you may not act. You can not prevent the death of millions by killing a single bystander. But you can not be prosecuted for inaction in that situation. While you can be prosecuted for pulling the lever, you might be deemed to be unable to be punished for it, yet that is by far not guaranteed. Jamming could be such a trolly situation, as jamming might kill people by making airplanes crash, or delay emergency vehicles.

Answer 3

A possibly relevant passage may be found in the FCC rules for the amateur radio service:

§ 97.403 Safety of life and protection of property.

No provision of these rules prevents the use by an amateur station of any means of radiocommunication at its disposal to provide essential communication needs in connection with the immediate safety of human life and immediate protection of property when normal communication systems are not available.

Similar provisions may exist for other radio services. I believe this provision would apply if Alice is authorized for use in a radio service that has such a rule. Of course, jamming a signal is not communications in the usual sense, but implicitly communicates the message "I, the person jamming the signal, will not allow the illegal activity."