if carrying out a contract makes both parties criminally liable, can you breach it?

I may be completely wrong, (I'm not a lawyer, not studying law, and don't know any lawyers) but isn't there a 'without prejudice' statement in most contracts, which covers this sort of thing?

The only without prejudice I know of is in documents between two parties when negotiating a settlement in which case without prejudice = this is not to be shown to the judge.

In this case it'd be void from the start.

Oh right, I remember a few years ago I accepted a voluntary redundancy from my job, and the company provided legal advice to take me through the contract, and they explained a without prejudice clause, from memory it was something about if any clause turns out to be illegal, that clause will be void but the rest of the contract is still valid.

It depends if performance of the contract would necessarily be illegal. If the contract can be performed in an illegal way and a legal way, then the contract is still valid (except if both parties in fact intend to perform it in an illegal way). If its performance is necessarily illegal then it is void.

If there is an express clause allowing for the severance of any clause that turns out to be illegal, then the contract as a whole will not be void if such severance is possible. It is capable of performance in a legal way, in accordance with the contract, by severing the illegal terms. Of course not every contract can be saved in this way, the contract might not have any consideration if the illegal clause is severed, or it might be manifestly contrary to public policy.

A contract is void ab initio if it would necessarily be illegal to perform the duties under it at the time it was made. It does not make sense to speak of 'breaching' the contract, because there is no valid contract to breach in those circumstances.

It depends if performance of the contract would necessarily be illegal. If the contract can be performed in an illegal way and a legal way, then the contract is still valid (except if both parties in fact intend to perform it in an illegal way). If its performance is necessarily illegal then it is void.

If there is an express clause allowing for the severance of any clause that turns out to be illegal, then the contract as a whole will not be void if such severance is possible. It is capable of performance in a legal way, in accordance with the contract, by severing the illegal terms. Of course not every contract can be saved in this way, the contract might not have any consideration if the illegal clause is severed, or it might be manifestly contrary to public policy.

thanks. I just read something about the defense of illegality - if there's no valid contract, what exactly is the defense for? Just a defense that they don't have to perform their contractual obligations because the contract was void from the outset?