Apart from Iraq there was nothing. Of course it was illegal. You can't even see a diplomat's papers for security checking and not even raid their private residence. The diplomat is off limits.
I meant that you avoid international backlash if you provide a solid reason. Illegal but avoidance of backlash in international community.
It's a pretty out of the box idea. :p
Oh it would be but you and I both know India would not get international backlash and its not bcz of the conspiracy theory that world loves India and hate Pakistan. The world would turn a blind eye on that illegal action.
Anyway let's not get dragged too deep into the nuke scenario.
In the end you are right that its illegal and very illegal and is seen as a provocation. You can ask them to vacate if relations deteriorate but you cannot search them since the diplomats and embassy is off limits.
However all laws draw their power from the authority that implements them thus without that proper impartial and non emotional authority, people break the law or in case of emotional authority, justify the breaking aka honor killing justified to a panchayat.