Maybe you are getting sued or maybe you are suing someone else. Perhaps it has nothing to do with suing, but is a custody battle over a child or a battle for rights over copyrighted property. The possibilities are nearly infinite, but you will know whether you have been involved in any troubling legal matters and can give testament to how true these allegations might be. Are you having run-ins with the law recently? Then this is the reason for the ace of clubs card showing up in your dreams. The ace is not an ominous sign in this case, just a marker of the current events which you should probably already be aware of.
When the ace of hearts appears in your dream, then this means that you are involved in an affair. This can be a blatant adulterous act such as extramarital sex with various other partners, but it does not have to be. Perhaps you have been naughty thoughts about someone else that you are not married to or involved with, and have been ignoring you significant other in order to continue with these thoughts. This would show that you have been unfaithful even though you have one nothing physically wrong. If all you can think about is another person then you have mentally cheated and this is why the ace of hearts is appearing to you in your sleep.
If you are dreaming of the ace of spades then this usually means that your life has been revolving around a scandal as of late. You have been caught doing something that you knew you should not have done or you have been caught in a compromising situation. This can have to do with anything from career prospects to your love lie, but a scandal is a scandal and dream symbols showing you of your wrongdoing are important signs for anyone that is tuned into their more clairvoyant tendencies.
The ace of diamonds acts as a symbol of your power and your legacy in the world. It shows your level of power over others and the kind of power you indirectly command. Have you heard others whispering tales of you in the locker room or have you overheard conversations about you? Good or bad, a situation like this can sue you into the fact that people are finally paying attention to you. You are starting to build a reputation for yourself and others are beginning to notice you.
Finally, another meaning that the dream might have would be the other definition of the world ace, which is to do well on a test or in a specific situation. When you perform well in certain circumstances, especially when you have been looking forward to them and practicing at them, then when you ace them, you may see a symbol in your dreams to mark the occasion. In this case it would be the symbol of an ace card.