Is this a legal use of force in the U.K.?
<p>A man is walking on a sidewalk. </p>

<p>A moped with two people riding swerves quickly  and deliberately onto the busy sidewalk. It drives on the sidewalk for a few seconds weaving dangerously amongst the pedestrians.</p>

<p>The man sees the oncoming moped, dances out of the way and gives a well timed kick against the moped to knock it off balance.</p>

<p>The moped riders fall off.</p>

<p>It this a legal use of force in the UK?</p>

<p>If another pedestrian was injured by the now riderless moped, is the kicker criminally responsible?</p>

<p>Citing the same <a href="http://www.cps.gov.uk/legal/s_to_u/self_defence/" rel="nofollow noreferrer">guide</a> as your earlier question <a href="https://law.stackexchange.com/questions/24029/is-this-legal-use-of-force-in-the-uk">united kingdom - Is this legal use of force in the UK?</a></p>

<blockquote>
  <p>In assessing the reasonableness of the force used, prosecutors should
  ask two questions:</p>
  
  <ul>
  <li><p>was the use of force necessary in the circumstances, i.e. Was there a    need for any force at all? and</p></li>
  <li><p>was the force used reasonable in the circumstances?</p></li>
  </ul>
</blockquote>

<p>Is the kick to knock the moped riders down necessary? Is it reasonable in the circumstances for the purposes of self-defence or defence of another?</p>

<p>Yes, you say they are</p>

<blockquote>
  <p><em>...weaving dangerously amongst the pedestrians.</em></p>
</blockquote>

<p>But would a prosecutor feel that a few seconds riding on the sidewalk really demonstrated that they are an imminent threat to pedestrians that required action on the part of the man to act in defense of others? And not to the kicker himself, since he jumped out of the way?</p>

<blockquote>
  <p><em>If another pedestrian was injured by the now riderless moped, is the kicker criminally responsible?</em></p>
</blockquote>

<p>The kicker could be criminally responsible, if the prosecutor wants to argue that his actions were unnecessary given the lack of imminent threat to the pedestrians and were more of a vigilante action than an action in the interest of public safety, even if if riding a moped on the sidewalk happened to be illegal in that area.</p>

<p>The kicker could be at least civilly responsible, if the injured find a solicitor who takes their case, as the tire kicker caused the accident. True, the moped riders were on the sidewalk, but that is really only relevant if riding a moped on the sidewalk is illegal and/or there is evidence - video, etc. - that the riding was dangerous.</p>

<p>The moped riders, if injured, could also consider civil action against the kicker, irregardless if riding on the sidewalk happens to be illegal.</p>

united-kingdom