A direct free kick is awarded if a player commits any of the following offences:
- handles the ball deliberately (except for the goalkeeper within their penalty area)
- holds an opponent
- impedes an opponent with contact
- spits at an opponent
An indirect free kick is awarded if a player:
- plays in a dangerous manner
- impedes the progress of an opponent without any contact being made
IMPEDING THE PROGRESS OF AN OPPONENT WITHOUT CONTACT (obstruction)
Impeding the progress of an opponent means moving into the opponent’s path to obstruct, block, slow down or force a change of direction when the ball is not within playing distance of either player.
All players have a right to their position on the field of play; being in the way of an opponent is not the same as moving into the way of an opponent.
A player may shield the ball by taking a position between an opponent and the ball if the ball is within playing distance and the opponent is not held off with the arms or body. If the ball is within playing distance, the player may be fairly charged by an opponent.
Even if there was obstruction, which there wasn't, a contactless impediment can never result in a penalty.
This is partly my fault because I was using informal language, but you're quoting the wrong section of the laws here. Although I do mean that Karius impeded Kane in the sense that he made him deviate from his course by diving at his feet, in terms of the law this situation on the pitch is much better described as a tackle and, therefore, governed by law 12.1.
A direct free kick is awarded to the opposing team if a player commits any of the following seven offences in a manner considered by the referee to be careless, reckless or using excessive force:
- kicks or attempts to kick an opponent
- trips or attempts to trip an opponent
- jumps at an opponent
- charges an opponent
- strikes or attempts to strike an opponent
- pushes an opponent
- tackles an opponent
2015/2016 very clearly states 3 instances where a foul can be given without contact necessarily being made, and – by implication – adds that contact need not be made in the other instances.
In 2016/2017 the line was added after this list to say 'if an offence involves contact it is penalised by a direct free kick or penalty kick' which you seem to have interpreted to mean 'only an offence involving contact is penalised by a direct free kick or penalty kick'. I can see
why you'd interprete it that way, it's poorly worded, but it's not what is actually said. It's a logical fallacy, not the intention of that line and is directly contradictory to the information, still present in the laws, that players can be sent off for attempts to do something, to argue this means you can only commit a foul if you make contact.
What the new wording intended to clarify, albeit badly, is that there are no instances where contact is made that can be given as an indirect free kick. As proved by the IFAB Q&A on the issue.
Q1: If an offence involves contact can it be an indirect free kick? NO – if an offence (including dangerous play) involves contact with the opponent it must be penalised with a direct free kick.
So the relevant law, as should have been obvious, is law 12.1. If a tackle is deemed to be careless, reckless, or using excessive force it's perfectly within the laws of the game (and something you see repeatedly with two footed challenges given as red cards without necessarily making contact) to give it as a DFK worthy offence and, if in the penalty box, a penalty. Whether Karius did tackle in a careless manner is a different issue, but it's an absolutely standard interpretation of the laws.
It's worth reminding ourselves of the basic requirements of a foul:
- it must be committed by a player
- it must occur on the field of play
- it must occur while the ball is in play
You'll note the absence of 'it must involve contact'. What Kane subsequently does or doesn't do is fundamentally immaterial to the question of whether Karius committed a foul or not. It was a correct decision.