When two parties enter into a contract, they are expected to fulfill their obligations as agreed upon. However, in some cases, one party may fail to carry out their part of the deal, leading the other party to seek specific performance of the contract. This means they want the court to order the defaulting party to fulfill their contractual obligations.

In such a situation, the defaulting party may mount a defence against the suit for specific performance. Here are some common defences used in such cases:

1. Impossibility of performance: If the performance of the contract has become impossible due to unforeseen circumstances such as natural disasters, war, or death of a party, then the defaulting party may use this defence. However, if the impossibility was foreseeable or could have been prevented, this defence may not hold.

2. Unconscionability: If the contract is found to be unconscionable, meaning it is excessively harsh or unfair, the defaulting party may argue that specific performance should not be granted.

3. Unclean hands: If the party seeking specific performance has acted in bad faith or has breached their own obligations under the contract, the defaulting party may argue that they have unclean hands and therefore should not be granted specific performance.

4. Inadequate consideration: If the consideration or the value exchanged for the performance under the contract was inadequate, then the defaulting party may argue that specific performance should not be granted, as it would be unjust.

5. Violation of public policy: If the performance under the contract violates public policy, such as a contract for illegal activities, then the defaulting party may argue that specific performance should not be granted.

It is important to note that the burden of proof for these defences lies with the defaulting party, and the court will consider various factors before deciding whether specific performance should be granted or not.

In conclusion, a suit for specific performance of a contract can be met with various defences from the defaulting party. It is important to consult with a legal professional to navigate these defences and ensure that the obligations under the contract are fulfilled.