Aseem Trivedi did nothing illegal by drawing the cartoons and putting them on the net.
In a democracy many things are said, some truthful and others false. I often used to say in Court when I was a Judge that people can call me a fool or crook inside Court or outside but I will never take contempt of court proceedings, because either the allegation is true, in which case I deserve it, or it is false, in which case I will ignore it. These are occupational hazards, and politicians , like Judges, must learn to put up with them.
Cartoons are part of democracy and part of the freedom of the media guaranteed by Article 19(1) (a) of the Indian Constitution. Hence arresting him was itself a crime called wrongful arrest and wrongful confinement under sections 341 and 342 of the Indian Penal Code, and those who arrested him should themselves be arrested and tried and given harsh punisment if convicted. It seems that some authorities in India are becoming increasingly intolerant, as in the case of arrest of a farmer by the Chief Minister of West Bengal only because in a public meeting he said that the Chief Minister had not kept her election promises.
In fact arresting a cartooniist or any other person who has not committed a crime is itself a crime under the Indian Penal Code called wrongful arrest and wrongful confinement.
If the policemen who arrested him say that they were only carrying out the order of some superior authority (whether political or administrative) this is no defence, because an official should not obey an illegal order. For instance, if a policemen is told by a higher authority to commit a murder or burglary or rape, he should disobey this illegal order, otherwise he should be tried and if found guilty given harsh punishment.
In the Nuremberg Trials the Nazi war criminals took the plea that orders are orders, and that they were not guilty as they were only carrying out the order of their superior Hitler. This plea was rejected and the International Tribunal said that they should have dosobeyed such orders as they were illegal, and accordingly many of them were hanged.
The charge of sedition against Aseem is wholly unsustainable since in 1962 in the case of Kedar Nath Singh vs. State of Bihar (which can be seen online) the Indian Supreme Court held that it is only speech which incites to violence which is seditious. Merely criticizing the government or creating disaffection against it is not sedition. In fact to hold otherwise would completely subvert democracy, in which people have a right to criticize the government. Aseem's cartoons certainly did not incite to violence, though they may have severely criticized politicians.
Politicians and police authorities must learn to be tolerant and take criticism in their stride. In a democracy it is the people who are supreme, and all authorities, whether political or administrative, are only servants of the people. Surely the master has a right to criticize his servant if he thinks that the servant has done something wrong.
The behaviour of the policemen who arrested Aseem was wholly illegal and unacceptable, since India is a democracy with a Constitution having the Fundamental Rights of freedom of speech and liberty.