A contingent liability is a potential liability...it depends on a future event occurring or not occurring. For example, if a parent guarantees a daughter's first car loan, the parent has a contingent liability. If the daughter makes her car payments and pays off the loan, the parent will have no liability. If the daughter fails to make the payments, the parent will have a liability.
If a company is sued by a former employee for $500,000 for age discrimination, the company has a contingent liability. If the company is found guilty, it will have a liability. However, if the company is not found guilty, the company will not have an actual liability.
If a contingent liability is only possible (not probable), or if the amount cannot be estimated, a journal entry is not required. However, a disclosure is required.
When a contingent liability is remote (such as a nuisance suit), then neither a journal nor a disclosure is required.
A product warranty is often cited as a contingent liability that is both probable and can be estimated. Additional examples and a further explanation are presented in FASB's Statement of Financial Accounting Standards No. 5, Accounting for Contingencies. This accounting pronouncement is available at www.FASB.org/st.