Wikipedia says). So here goes.
Can the contract be enforced against you? A valid contract is one that a court will enforce. Some reasons your contract might not be enforceable are if (1) it violates the law or public policy, (2) there's no consideration -- you didn't receive any benefit from the arrangement, (3) the other side fraudulently induced you to sign, or (4) you were coerced (duress) into entering into the agreement. If fraud or duress are present, then you can void the contract. All parties are released from their obligations and you can pursue your claims against the band. In cases of intentional fraud—for example, if a band mate deliberately lied to induce a deal, you can elect to seek additional damages under tort law. (BTW, even if the agreement is valid, you may also have claims that the other side breached it, thereby terminating the agreement.)
What is duress? Duress occurs when a party’s consent to a contract is physically or mentally coerced. A party under duress lacks the legal free will to refuse to sign. Therefore, the agreement is not voluntary and the contract that results must be voided. Threats of physical force are rarely used as a means of inducing a contract. Instead, economic duress has emerged as a bigger issue. Economic duress (also known as “business compulsion”) occurs when, for example, a supplier of goods jacks up the price on a customer who is in desperate need of goods, or one party threatens to breach an existing contract unless the other party agrees to some further demand. But keep in mind that proving duress in a court or at an arbitration -- which is where you'll have to prove it -- requires more than threats. You'll also need to show you had no other choice but to comply, a sometimes difficult task.
Does the agreement transfer copyright? The musical compositions and the musical performances are works that are subject to copyright. In order for the band to acquire those rights, the agreement (or some other written agreement) must specifically transfer these rights. If the agreement doesn't say anything about copyright ownership, your rights in those works may be unaffected and you are probably free to register your rights in your name. Along with that, you can exploit your interest in the songs and collect royalties for their use.
Bottom Line Dept. If you want true closure, you should see a music attorney.