The 1937 Act introduced some additional grounds for divorce, but the process was still complex and difficult — requiring for example strict proof that one of the specified ‘offences’ had been committed, and also evidence that the parties had not ‘colluded’ in concocting a case. All this gave rise to much legal difficulty and the courts had to grapple with issues such as whether the fact that a man was insane (and thus not liable under the criminal law) also meant that he could not be guilty of the ‘offence’ of cruelty. And what degree of bad behaviour would give husband or wife the legal right to leave his or her spouse? This had to be distinguished from the ‘ordinary wear and tear of married life’.