In an effort to limit inventors to one invention per patent, the United States Patent Office (“USPTO”) allows patent examiners to require applicants to limit their patent application to one invention. This creates a quandary for applicants. On the one hand in order to obtain broad coverage of an invention, current case law encourages an inventor to disclose variations (“embodiments”) of their invention to avoid the "single embodiment squeeze” where the claims in a patent may be interpreted more narrowly than if there were multiple embodiments in the patent. On the other hand, when an applicant files a patent application with multiple embodiments, it will often invite a restriction requirement from the USPTO. What is a patent owner to do?

Certainly limiting an application to a single embodiment can help avoid a restriction requirement (though not guaranteed), but it may not give you the best coverage. Hence, if an applicant wants to seek the best possible coverage for their invention, it is usually best to be prepared to write the patent application with multiple embodiments, and then manage any restriction requirement.

The easy solution to dealing with a restriction requirement is to pick one invention to pursue at that time, and then file what is referred to as a “divisional application” on the claims that you did not pursue at that time—but this adds to the expense on several levels. First there are the divisional filing costs and fees, and then later the prosecution costs and fees, then followed by the additional issue fees and maintenance fees.
There are some approaches when drafting the application, especially the claims, that can avoid or minimize restriction. These approaches are best formulated in the initial application drafting phase, and most often cannot be addressed after the fact. While there can be options to tie some inventions together even if you miss your first opportunity—they are no substitute for good planning.